1. The sides of a triangle are all integers, and the perimeter is 9. The number of non-congruent triangles is ( ).
(A) 1
(B) 2
(C) 3
(D) 4
- 1. C.
$$
9=4+4+1=4+3+2=3+3+3 \text {. }
$$

- 1. C.
$$
9=4+4+1=4+3+2=3+3+3 \text {. }
$$