Factory janitors wages are

a. a product cost and direct material cost
b. product cost and direct labor cost
c. product cost and factory overhead cost
d. period cost and selling expense period cost and
e. administrative expense

c. product cost and factory overhead cost

Explanation:

A janitor's wage is a maintenance overhead cost, as it is the wage of a maintenance staff member. As such, it does go in the total product cost, but not in the form of direct labor cost. Instead, it belongs to factory overhead costs, together with other factory maintenance costs.

This is not a direct labor cost, as it is not directly involved in the manufacturing process. Instead, it is supporting it.

reducing the scale of the market for a new product.

answer/// equals both average variable cost and average total cost at their respective minimums;