The average annual income, I, in dollars, of a lawyer with an age of x years is modeled with the following function: I = -425x^2 + 45,500x - 650,000. According to this model, what is the maximum average annual income, in dollars, a lawyer can earn? Round to the nearest whole dollar.
a. $425,000
b. $550,000
c. $650,000
d. $750,000
