From the question stem it looks like an inference question

(A) Some part of the panthers’ current habitat is only of marginal quality.
Irrelevant and not mentioned anywhere in the passage.

(B) If the population of Florida panthers ever exceeds 250, it will be self-sustaining.
It is directly mentioned in the passage.

(C) Unless Florida panthers acquire a larger habitat, their population will not be self-sustaining.
Can be inferred from the passage. Till the time population doesn't reach 250 its not self sustaining and in current habitat the population cant grow hence in current habitat population cannot be self-sustaining. Correct.

(D) The population of Florida panthers will never increase much beyond its current level.
if the size of the habitat increases then the population can increase. Incorrect.

(E) Today, Florida panthers occupy a larger habitat than they did in the 1970s.
Cant be concluded from the passage. Maybe the habitat was bigger and Panthers were dying due to another reason like hunting.

Hence C is the correct answer.

Can someone explain why B is incorrect?

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"The population must reach at least 250" is one condition which should be true in order to make the population self-sufficient.

In an option B

there is an assertion: if this condition is true, the population will be self-sufficient......Hence, B is incorrect because there could be other factors may affect to make the population self-sufficient.

Thanks = Kudos

Firstly, It is only between B and C.
I picked B over C so I want someone to give a better reasoning for C.

Or B can only be eliminated on the basis that it is already mentioned in the passage?

Thank you!
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Hi everyone,

So between B and C.

We know that ONE OF THE CONDITIONS for the panthers' population to be self sustaining is the number, 250. We also know that the current habitat does not support more than 100 panthers.

In order to eliminate B let's consider the following scenario: Enough panthers are introduced in the current habitat so that the minimum 250 is met. The problem now is that the current habitat won't support the extra ones and probably all the tigers but 100 of them will die.

Hence Option B is not a must be true statement.