The equation - 5x² + 72x + 378 models the number of students enrolled in a school where x is the number of years since the school first opened in 1990. Which equation can be used to find the year in which 502 students were enrolled?
A. - 5x² + 72x - 124 = 0
B. - 5x² + 72x + 502 = 0
C. - 5x² + 72x - 502 = 0
D. - 5x² + 72x + 124 = 0