Identifying the factored form of a trinomial which expression is the factored form of x2 – 7x + 10?

Let's call x^2: a; -7x: b; and 10:c
So what I do in this case:
when the number squared does not have a coefficient in front, I ask myself, what does A times C equal
the answer is 10 --> now what factors of ten, add up to -7 (the factors can be negative and/or positive)
the answer is -2 and -5
so with this, you do: (x-2)(x-5)
there's your answer, i hope that makes sense

The answer is a because i went through all the other ones that it didn’t come out right