Final answer:
The expression (a+b+c)(d+e+f) consists of two factors, each trinomial itself.
Step-by-step explanation:
The expression (a+b+c)(d+e+f) represents the multiplication of two trinomials. To determine how many factors the expression has, it is important to understand that in this context, each of the binomials is a single factor. Therefore, the expression has two factors: (a+b+c) and (d+e+f). It is not the expansion of the product that is being asked for, but the number of factors making up the expression. So the answer to how many factors are in the expression (a+b+c)(d+e+f) is two.