Choice C is the correct answer. We need to factor $x^2 + 3x - 10$. We seek two numbers that multiply to -10 and add to +3.

1. Factors of -10: (-1, 10), (1, -10), (-2, 5), (2, -5).
2. Sums: $-1+10=9$, $1-10=-9$, $-2+5=3$, $2-5=-3$.
3. The correct pair is -2 and 5.

So, the expression factors as $(x - 2)(x + 5)$. Therefore, $(x - 2)$ is one of the factors.

Choice A is incorrect because the factor is $(x+5)$, not $(x-5)$. Choice B is incorrect because the factor is $(x-2)$, not $(x+2)$. Choice D is incorrect because 10 is not part of the correct factor pair.