Which expression is the exponential form of $(\sqrt[3]{a})^2$?
A$(\sqrt{a})^{3 / 2}$
B$a^{2 / 3}$
C$(\sqrt{a})^{2 / 3}$
A$(\sqrt{a})^{3 / 2}$
B$a^{2 / 3}$
C$(\sqrt{a})^{2 / 3}$