Interested

#help Is my logic logic-ing

The example stated says that the traffic jam makes it impossible to fulfill the promise.

The conclusion states that ought→can - not always true

So

ought -> can

ought-> can't

or

not ought -> can

ought -> can

Comparing the two statements you can infer that promise → ought

The answer choice D fulfills the need that the impossibility or can't doesn't negate the ought because that would make the conclusion false. Then everything you are ought to do is possible because if it wasn't possible then the ought is negated.

This question got me good.

Premise: A study tells us that doing X reduces accident rates.

Conclusion: We should do X.

The principle applied that connects the premise and conclusion:

Any measure that reduces accident rates should be implemented.

I think the word "Since" Made me think that, that was support I need to link to the conclusion. However the word since, the way it was applied, refers to what the study dictates as the speed limit. That bit of information was just disposable context inserted to make the question more difficult.