The graph represents the data cost for monthly internet service for a cell phone. Which function, C(x), respresent the monthly cost in dollars in terms of x, the number of gigabytes used in a month?

Correct option: first one

Step-by-step explanation:

The graph has 3 different parts:

Cost = 15 when the Gigabytes used is lesser than or equal 2,

Cost from 20 to 40 when the Gigabytes used is greater than 2 and lesser than or equal 6.

An increase of 4 gigabytes caused an increase of 20 in the cost, so the slope is 20/4 = 5, and the y-intercept is:

20 = 5*2 + b -> b = 10

Cost = 50 when the Gigabytes used is greater than 6.

So the correct option is the first one