Critical Reasoning

7. If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?
(A) If D, then A.
(B) If not B, then not C.
(C) If not D, then not A.
(D) If D, then E
(E) If not A, then not D.

IMO E

IMO C

The question doesn't say there are no ways to arrive at D other than
A -> B -> C -> D.
So, we cannot say E

But, if A happened then B happens, then C happens, and then D happens. So, if D didn't happen then A wouldn't have happened. In other words 'If not D, but A happens' is NOT possible. So (C).

I'd go with C.

Easy pick.. Cause effect relation
It should be C undoubtedly

I didn't get it. I look at the problem this way

If A doesn't happen, B will not happen
same way if not B then not C and then not D

so If not A then not D ??????

what 's the mistake?, but this way we end up with two correct answers B and E.

BMlaud, you're looking at it backwards. It's C. As someone pointed out above, the problem doesn't say that A causing B causing C is the *only* way to get to D. It only says that if A happens, then B, C and D have to happen.

Translate it into real-world terms. "If it rains, the streets get wet." That means that if the streets are *not* wet, we can say that it hasn't been raining. But you can't say that if it doesn't rain, the streets won't get wet. Maybe the streets will get wet from people watering their lawns.

More parallel to this problem, suppose it's "If if rains, the streets get wet. If the streets get wet, car accidents happen. If car accidents happen, people get injured." So you can conclude from that that if no one is injured, it hasn't been raining. But you *can't* conclude from that that if it hasn't rained, no one has been injured. Other factors could cause injuries. Other factors could cause car accidents. And other factors could cause wet streets.

Thanks Karen,

The example that you have given makes it clear.

Principle of logical reasoning,
If A happen then B will happen.
Right Conclusion: If B doesn't happen then A doesn't happen.

Wrong Conclusion: If A doesn't happen then B doesn't happen.

Reason being A produce B this doesn't not mean that A is the only source through which B is happening it can happen due to C too. But if B is not there then surely A is not there.

If you apply this concept answer is C.

You can solve this question through sets - let them be A, B, C, D.

А)----B)-----C)-----D)
A is the part of B, B is the part of C, C - part of D. Obviuosly, A is the part of D.

Answers
(A) If D, then A.
Variants
А)----B)-----C)--*---D)
А)----B)--*---C)-----D)
А)--*--B)-----C)-----D)
if * is the part of D, it doesnot guarantee that * belongs to A.
INCORRECT

The same with other answers
(B) If not B, then not C.
А)----B)--*---C)-----D)
А)----B)-----C)--*---D)
INCORRECT

(C) If not D, then not A.
А)----B)-----C)-----D) *
CORRECT

(D) If D, then E.
INCORRECT

(E) If not A, then not D.
INCORRECT


С

Ans C
causal logic.
if a --> b then if not b means not a.