Let $z = x y$ , and Let $x$ And $y$ Be Functions Of

Multiple Choice

Let $z = x y$ , and let $x$ and $y$ be functions of $t$ with $x ( 1 ) = 1 , y ( 1 ) = 2 , x ^ { \prime } ( 1 ) = 3 \text {, and } y ^ { \prime } ( 1 ) = 4$ . Find $d z / d t$ when $t = 1$ .

A) 5
B) 6
C) 7
D) 8
E) 9
F) 10
G) 11
H) 12