$\begin{array}{1 1} \text{a. The shadow of the tree changes but the size remains the same.} \\ \text{
b. The size of the shadow of the tree changes but shape remains the same.} \\ \text{
c. Both size and shape of the shadow of the tree change} \\ \text{
d. Neither the shape nor the size of the shadow changes.}
\end{array}$
