I’m having trouble with this unit. can anyone explain?

the option B is right graph.

explanation:

as shown in table data,

if we draw these points on graph and join all points we will get 2nd graph. to verify lets check if points exist on line or not.

so first point in our table is

on 15 messages charge is 26.50 dollar.

in 2md graph we can see that at 25 messages on x axis we have value of 26.50 dollar on y axis.

similarly second dataset is also lies on our line that is on 20 message charge is 27 dollar.

in similar manner we can verify that all points of table are lies on line in graph 2

the answer is a

step-by-step explanation:

because if you put 1 in to the square root of x it equals 300.

there is no question content here, but you for the free points! : d