What is the most convenient method to solve the following system of equations? Express the solution set in terms of one of the variables. Leave all fractional answers in the form of x + 3y = -7.

A) x + 3y = -7; y - 5z = 22; -2x - 7y + 6z = 4
B) x + 3y = -7; y - 5z = 22; -2x - 7y + 6z = 4
C) x + 3y = -7; y - 5z = 22; -2x - 7y + 6z = 4
D) x + 3y = -7; y - 5z = 22; -2x - 7y + 6z = 4