When multiplying $(x+m)(x+n)$ using FOIL, which pair of terms combine to produce the $bx$ term in $x^2+bx+c$?

The outside and inside terms, $m\cdot x$ and $n\cdot x$, which combine to $(m+n)x$

The first and last terms, $x\cdot x$ and $m\cdot n$, which combine to $x^2+mn$

Only the last terms, $m\cdot n$, produce the $bx$ term because constants can become coefficients if combined with $x$ later on

The outside and last terms combined with a distributive rearrangement that produces the middle term after simplification