If we wanted to verify that y = c sin(r) + C2 cos(r) +2 + x2 is a general solution for the differential equation y" + y = 4 + x2, then what must we check? Mark all that are necessary. DA. Y1 = 2, y2 = x' are linearly independent. OB. Y1 = sin(x), y2 = cos(x) are continuous functions. Oc. Yp = 2+ r is a particular solution for y" +y = 4+ x?. OD. y1 = 2, y2 = x' are continuous functions. ODE. Y1 = sin(x), y2 = cos() are a fundamental set of solutions for y" + y = 0. OF. None of the above