17 * 197 The number of triangles with side lengths being the prime factors of 1995 is
(A) 4.
(B) 7.
(C) 13.
(D) 60.
(China Hebei Province Junior High School Mathematics Competition, 1995)
[Solution] $1995=3 \times 5 \times 7 \times 19$, the triangles that can be formed are:
Equilateral triangles: $(3,3,3),(5,5,5),(7,7,7),(19,19,19)$;
Isosceles triangles: $(3,3,5),(5,5,3),(5,5,7),(7,7,3),(7,7,5)$,
$$
(19,19,3),(19,19,5),(19,19,7) \text {; }
$$

Scalene triangles: $(3,5,7)$.
In total, there are 13.
Therefore, the answer is $(C)$.