You are buying packages of beads to make bracelets. Each package costs $3 plus 7% tax. You have a gift card for $15, and you plan to use only the gift card to pay for the beads. Which function c(p) represents the total cost, where p represents the number of packages of beads you purchase? What is a reasonable domain?

A. c(p) = 3.21p − 15; {0, 1, 2, 3, 4}
B. c(p) = 3.21p; all nonnegative integers
C. c(p) = 0.07(3p − 15); all nonnegative integers
D. c(p) = 1.07(3p); all nonnegative integers