Logical reasoning PrepTest 102 · Section 4 · Question 18

Incorrect. Experience pain → Mistreated. This answer is a negation of the answer we're looking for. Plants can't experience pain, so this answer doesn't apply to them.

Incorrect. Experience pain → Nervous system. This answer restates the second premise, so it adds nothing to the argument.

Incorrect. Nervous system → Experience pain. This answer is a reversal of the second premise, so it doesn't add anything to the argument. Plants don't have nervous systems, so this answer doesn't apply to them.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Sufficient Premise

Stimulus Summary:
Plant → not Nervous system
Experience pain → Nervous system
Therefore - We can't mistreat plants

Answer Anticipation:
Strengthen with Sufficient Premise questions frequently deal in conditional logic. They also frequently introduce new concepts in the conclusion. When both of these happen, the correct answer usually connects a conditional chain in the premise(s) to that new term in the conclusion.

First, the structure here. The "Obviously" at the beginning could highlight a premise or a conclusion. However, the fact that the next two statements are connected with "and" means that they serve the same function in the argument, and since they can't be co-conclusions, they're premises. Those premises are also seemingly in support of the first, making that first statement a conclusion.

Here, the premises are conditional—it talks about what is true of all plants, and what "is necessary" to experience pain. They also share a term, but we need to take the contrapositive of one statement to combine them. Since the conclusion talks about plants, let's take the contrapositive of the second statement so we don't end up with not Plants:
Plant → not Nervous system → not Experience pain
Therefore - We can't mistreat plants

So the premises let us conclude that plants can't experience pain, and the conclusion is that we can't mistreat plants. That assumes that something that can't experience pain can't be mistreated, or:
not Experience pain → not Mistreated
(or the contrapositive)
Mistreated → Experience pain

Answer Explanation:
Mistreated → Experience pain. This answer matches our anticipation (or, at least, the contrapositive of it). It guarantees that anything that can't experience pain can't be mistreated, and plants can't experience pain since they lack a nervous system. Added to the argument, this answer completes the chain and allows the conclusion to be drawn, so it's correct.

Key Takeaway:
When Strengthen with Sufficient Premise questions feature conditional logic and a new concept in the conclusion, the correct answer will almost always be a conditional statement that connects that new concept to something from the premises. Chain together any premises that you can, get them to line up with the conclusion, and then find the missing link.

Incorrect. Nervous system → Mistreated. But plants don't have nervous systems, so this answer doesn't apply to them.