$32 \cdot 17$ Among the integers $0,1,2,3,4,5,6,7,8,9$, let the number of prime numbers be $x$, the number of even numbers be $y$, the number of perfect squares be $z$, and the number of composite numbers be $u$. Then the value of $x+y+z+u$ is
(A) 17.
(B) 15.
(C) 13.
(D) 11.
(2nd "Hope Cup" National Mathematics Invitational Competition, 1991)
[Solution] Among the given integers, the prime numbers are $2,3,5,7$, a total of 4; the even numbers are $0,2,4,6,8$, a total of 5; the perfect squares are $0,1,4,9$, a total of 4; the composite numbers are $4,6,8,9$, a total of 4.
In total,
$$
4+5+4+4=17 \text{.}
$$

Therefore, the answer is $(A)$.