Choice A is the correct answer. Use the FOIL method (First, Outer, Inner, Last) to expand the product of two binomials.

1. First: $x \times x = x^2$
2. Outer: $x \times (-2) = -2x$
3. Inner: $5 \times x = 5x$
4. Last: $5 \times (-2) = -10$

Combine like terms: $x^2 + (-2x + 5x) - 10 = x^2 + 3x - 10$.

Choice B is incorrect because $5x - 2x = +3x$, not $-3x$. Choice C is incorrect because it adds 5 and 2 instead of subtracting. Choice D is incorrect because $5 \times (-2) = -10$, not +10.