Which graph represents y as a function of x?
A) A
B) B
C) C
D) D

The answer is A. You need to perform the vertical line test on it in order to solve.  If you draw a vertical line on it it will pass the line at only one point,

Step-by-step explanation:

3.4 pizzas

step-by-step explanation:

given is a scatter plot showing number of pizzas sold during weeks for different issues of coupon

y represents number of pizzas sold and x number of coupons issued

y is marked verticaly and x horizontally

the trend line is given as

y =3.4x+43

this says that even when no coupon is issued pizzas sold will be 43

and rate of change of pizza sold for 1 unit of coupon = slope = 3.4

i.e. when x increases by 1 unit y increases by 3.4 units

hence for each additional coupon issued 3.4 pizzas more will be sold