Which expressions have exactly two foctors? Choose ALL that apply. ny 2 \( 3(b-1) \) \( a+7 \) 4.n.n \( m^{2}+8 \)

To determine which expressions have exactly two factors, we can look for expressions that can be factored into two parts or are already presented in a factored form. - The expressions \( 2 \) and \( 4.n.n \) (which is \( 4n^2 \)) can be factored into two parts simply as \( 2 \times 1 \) and \( 2n \times 2n \), respectively. - \( 3(b-1) \) also exhibits two factors, namely \( 3 \) and \( (b-1) \). - The expressions \( a+7 \) and \( m^{2}+8 \) cannot be factored into two distinct factors over the integers, making them not applicable here. Thus, the expressions with exactly two factors are \( 2 \), \( 3(b-1) \), and \( 4.n.n \).