Which relation is a function?

A. (8, –4), (8, 4), (6, –3), (6, 3), (0, 0)
B. (4, 7), (8, 5), (6, 4), (5, 3), (4, 2)
C. (0, 0), (1, 1), (2, 2), (3, 3), (4, 7)
D. (0, 0), (1, 0), (1, 1), (2, 1), (1, 2)

Sundar used linear combination to solve the system of equations shown. he did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. what number did sundar multiply the second equation by? 2x+9y=41 3x+5y=36