given function is f(x)=16-x^2/3
to find the values of c we will convert function in terms of c
f(c)= 16-c^2/3
differentiate the function with respect to c
f'(c)= -2/3 c^-1/3 (1)
since f'(c)=0 is given
we can equate (1) to zero
-2/3 c^ -1/3 =0
c^-1/3=0 implies c=0
Option B can be concluded from the given question.
NOTE: it does not violate the Rolle's theorem hence, option A,C are discarded
option D is discarded because function is Differentiable .