When will the average velocity be equal to the instantaneous velocity?

Question

$\begin{array}{1 1} (a)\; \text{when the body is moving with a uniform velocity} \\ (b)\; \text{when the body is moving with a non-uniform velocity} \\ (c)\; \text{when the body is moving with a uniform acceleration } \\ (d)\; \text{when the body is moving with non-uniform acceleration} \end{array}$