Choice A is the correct answer. Since 2 is a root, it must satisfy the equation.

1. Substitute $x=2$: $2^2 - 5(2) + k = 0$.
2. Simplify: $4 - 10 + k = 0$.
3. $-6 + k = 0 \Rightarrow k = 6$.

Alternatively, Sum = 5. One root is 2, so the other is 3. Product $k = 2 \times 3 = 6$.

Choice B is incorrect because it is the other root. Choice C is incorrect because of sign error. Choice D is incorrect.