This type of question is really important to capture flaws in our reasoning. I see that in the comments there is debate about A being right because it fails to clearly communicate how the lack of intensity of projectiles striking Mars during the LHB period would show no support for hypothesis 2.

But I do think A can be seen as ruling out and failing to support hypothesis 2. This is because the time period mentioned allows us to make the inference that we would see an increase in intensity of projectiles striking Mars during the period '3-4' billion year period, while seeing a decline in the '4-5' billion year period. However, if as A says there is a lack of evidence for the increase in intensity during the 3-5 billion years, either before or after the conclusion as hypothesis 2 would suggest, then hypothesis 2 is not supported at least for one inner solar system planet—Mars.

Hi Kevin!

@jwmiller238 Wrong. The LR section is not proven to be significantly more difficult on new tests. What everyone is likely seeing is that test-day environments can affect your scores to make them different beacuse of the differences in environement when compared to their PT environment.

@Tania P. negation of a conditional (ex. P-->Q) is to get the sufficient condition and keep it, while adding a conjunction/AND and negating the necessary condition.

So negation of (/explain H and C ---> /explain basics) is:

/(explain H and C) AND (explain basics)

You might wonder why negating the necessary resulted in removing the negation and leaving us with (explain basics). That is because it was already negated and double negating just cancels out the negation. For instance: explaining basics is logically equivalent to //explaining basics.

@Deybomb17 I agree. If you do it in the way the course is set out, it becomes easier to understand because it builds the foundations he refers to.

@AudreyGilmour exactly. Had to think of this while I was doing my analysis after getting it right but wrong on BR. It makes sense because the first rule can give us a 'should not receive award' conclusion, while the second rule makes it impossible to get to that. Therefore, because the second rule is the only one applying to the saving a life and exceeding reasonable expectations, it cannot be used with B to get to the conclusion that Officer Penn should not receive the award. It just can go as far as to say Officer Franklin should receive it, but Officer Penn under this rule can still 'should' receive it for reasons other than those listed, and nothing tells us should not.

negative rules in answers signal wrong answers because they give us nothing that can explain what rule applies to the premises and conclusion to make the reasoning justified.