A family plan for a cell phone has a monthly base price of $99 plus $12.99 for each additional family member added beyond the primary account holder. Write a linear function to model the monthly cost, C(x) in dollars, of a family plan for x additional family members added. 1) C(x) = 99x+12.99 2) C(x) = 99x -12.99 3) C(x) = 12.99x+99 3) 4) c(x)=12.99x-99