The number of terms in the expansion of $(x+y+z)^n$ ________

Question

$\begin{array}{1 1}(A)\;\large\frac{n+1}{2}\\(B)\;\large\frac{n+2}{2}\\(C)\;(\large\frac{n+1}{2})(\large\frac{n+2}{2})\\(D)\;\text{None of these}\end{array}$

Comments

The  correct answer is D.
And the answer of the question is (n+1)(n+2)/2