+ Give the order of the differential equation below, where y represents a function of the variable x. -3y" +3y+y+y=6 Choose the correct answer below. OA. The given equation is a first-order differential equation because it involves a first derivative but no higher derivative. OB. The given equation is a first-order differential equation because it only involves a first derivative. OC. The given equation is a second-order differential equation because it involves a second derivative but no higher derivative. OD. The given equation is a third-order differential equation because it involves a third derivative but no higher derivative.