If the system of linear equations x1 + 2x2 + 3x3 = 6 x1 + 3x2 + 5x3 = 9 2x1 + 5x2 + ax3 = b is consistent and has infinite number of solutions, then
(A) b = 15, a can be any real number
(B) a ∈ R – {8} and b ∈ R – {15}
(C) a = 8, b can be any real number
(D) a= 8, b = 15
