Answer
(c) is incorrect.
Work Step by Step
a) Correct, because exponents add.
b) Correct, because multiplying exponents gives $\frac{1}{2}\times\frac{4}{3}=\frac{2}{3}$
c) Incorrect because:
$3^2 2^3=9(8)=72\neq 1$
d) Correct, because:
$(2^{-2})^{-2}=2^4=16$
