C-01-Q070mediumsingle_mcqx(x+1)(x+2)(x+3)+1x(x+1)(x+2)(x+3) + 1x(x+1)(x+2)(x+3)+1 equals—a(x2+3x)2(x^2 + 3x)^2(x2+3x)2b(x2+3x+1)2(x^2 + 3x + 1)^2