Ricardo pays a $70 sign-up fee to join a fitness center and $30 for each month of his membership. the equation c = 30m + 70 gives the total cost for m months. which statement correctly describes what happens when m increases? a. the number of months increases, but the sign-up fee and the total cost stay the same. b. the number of months and the total cost increase, but the sign-up fee stays the same. c. the number of months, the sign-up fee, and the total cost all increase d. the total cost increases, but the number of months and the sign-up fee stay the same.