Answer: option D. 2 is a coefficient.
Step-by-step explanation:
1) The expression 4 (2m - n) is a polynomial in its factored form.
2) There are two factors: 4 and 2m - n
3) The second factor, 2m - n, is a binomial. It means that it is formed by two monomials or terms: 2m and n.
4) The number in front of a term, in this case 2m, is named coefficient. Therefore, the number 2 is the coefficient of the term 2m.
In general, a term is a monomial, which is a expression of the kind:

Where:
- α is the coefficient
- x, y, ans z are the variables
- a, b, and c are the exponents of each variable
- a+b+c is the degree of the term