Answer: B. Negative
Reasoning:
'a' is less than 0, so we write a < 0
Since a < 0, this means a^4 > 0. Raising a negative to an even exponent will make the result positive. Example: (-2)^4 = 16
Applying the cube root to some positive number leads to some other positive number.
So far we see that the expression a^(4/3) is positive
The final result however is negative because the negative out front flips things from positive to negative.
It turns out it doesn't matter if 'a' is positive or negative. As long as 'a' is nonzero, then -a^(4/3) is negative. If a = 0, then the whole thing is 0.