The Sizes of Two Matrices a and B Are Given $2 \times 1$

Multiple Choice

The sizes of two matrices A and B are given. Find the sizes of the product AB and the product BA, whenever these
products exist.
-A is $2 \times 1$ , and $B$ is $1 \times 1$ .

A) $\mathrm{AB}$ does not exist; $1 \times 2$
B) $2 \times 2 ; 1 \times 1$
C) $1 \times 2 ; 1 \times 1$
D) $2 \times 1$ ; BA does not exist.