[题目]设随机变量X与Y相互独立,且 sim B(36,dfrac (1)(6)-|||-()sim B(12,dfrac (1)(3)) ,则 D(X-Y+1)= ()()-|||-A. dfrac (4)(3)-|||-B. dfrac (7)(3)-|||-C. dfrac (23)(3)-|||-D. dfrac (26)(3)