I also had the same issue, could you clarify this for me a bit more. Also why does the elimination of the word only make this particular approach correct

The quick answer to this of how I solved this problem between A and B for the two answer choice is that A is basically saying sufficient but not necessary whereas, B is saying something along the lines of bulging can be necessary for back pain but having it is not sufficient as indicating back pain. Granted this is a flaw question so the answer choices were slightly more different which is why I think they introduced the words partly in both answer choice.

Personal Take on the Question

Minor Premise 1: Most people favour the bill [LABEL A]

Minor Premise 2: The bill does not violate anyone's basic human right [LABEL B]

Minor Premise 3: Adversely affect those who are influential [LABEL C]

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Subconclusion/Major Premise: It will not be passed for many years, or might not be passed at all (rephased: it will not be pass promptly) [LABEL X]

PSAr Need (Premise Needed): X → Y

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Conclusion: Not a well functioning democracry [LABEL Y]

Answer Choice E (grammeratically broken down) : Well-functioning democracy (/Y) → (Bill does not violate human right (A) & most people favoured (B) → passed into law promptly (/X))

Analysis: We are told that A and B are true in the stimulus. This means the sufficient condition in the nested conditional is met so the condensed or factored (mathematical term) version would be:

Well-functioning democracry → Passed into law promptly

/Y →/X

This is the contrapositive of what we need, hence, making E the correct answer. As others stated because this is a PSA question, so C was probably not mentioned in the answer choice as a bit of flexibility is allowed.

Other answer choice lawgic (Note a lot of these are condensed from the outset using De Morgan's Law):

A: /Y → (benefit most people & B →passed into law)

Analysis: As JY said we need most favour not benefit most and we need it to be promptly passed into law

B: /Y → (A & C→ passed into law)

Analysis: Similar to answer choice A we need the bill to be passed promptly for the bridge to be built, eventually does not cut it

C: /Y → (A & /C → in a few years passed into law)

Analysis: I guess a few year can be considered prompted enough but one of the sufficiency condition fails so we have no way of knowing if the necessary condition will be met

D: /Y & Passed bill → A & consistent with individual basic human rights

Analysis: Not even sure how to relate this to the stimulus as it is unrelated on many levels

This is my understanding after watching the explanation video and hopefully this reduces the hair pulling for why the correct answer choice is correct,

The conclusion stating that "this approach" is flawed is targetting the very idea that what is real is depedent on the most explanatory powerful theory [MEPT].

(Given that this is the biconditional statement it might be easier to observe this from reverse of the statement as MEPT → real )

Here is the (supposed) tricky part to understanding this argument: this MEPT is simply a theory (has not yet been witnessed empirically, MEPT is a subset of theoretical "theories") and it is based on this theory that they are saying that it is real (as it is the most explanatory powerful theory that currently exists in the world of science.

The only premise offered is this:

P) Majority of science theories are theoretical

And so they conclude:

C) MEPT real [THIS IS FLAWED]

(Broken down, real→ MEPT, MEPT →real)

So the bridge or question that needs to be ask is one of the two

1) Why is being a theory flawed?

This leads to something along the line of a principle of:

Only based theory → Cannot be real

2) Why is being real mean a theory is flawed?

This leads to something along the line of a principle of:

Something that is real → Cannot be explained by a theory alone

This is what answer choice B is saying that theory on its on cannot be real (option 1).

In the end, for a biconditional to work it must work both ways and the approach given in the scientific community is not justified because they are effectively saying theories→ real but B is downright refusing that this is true!