Solution:
The zoo has 288 mammals.
Number of female mammals is 25% * 288 = ¼ * 288 = 72.
Number of male mammals is 288 - 72 = 216.

Consider first (1) alone.
Let the number of female mammals who were not born at the zoo be x.
So the number of male mammals that were born at the zoo is 3x
Also the number of female mammals that were born at the zoo is 72 - x.
The number of male mammals who were not born at the zoo is 216 - 3x.
So number of mammals born at the zoo is 3x + 72 - x = 72 + 2x.
We need this value (72 + 2x)/288 * 100.
Since more information is required to get the above value, (1) alone is not sufficient.

Next consider (2) alone.
Let the number of male mammals born at the zoo be y.
So the number of male mammals not born at the zoo is 3y.
So at most what we get is y+3y = 216.
Or y = 54.
But we need more information regarding number of female mammals born or not born at the zoo to answer the question.
So (2) alone is not sufficient.

Next combine both the statements together and check.
On combining, we have that 3x = 54.
So x = 18.
So 72+2x = 108.
From this we can calculate the required % 108/288 * 100.

The correct answer is (C) .