Answer the following questions using the information below:
The following information is for the Jeffries Corporation:

Assume the sales mix consists of three units of Product A and one unit of Product B. If the sales mix shifts to four units of Product A and one unit of Product B, then the weighted-average contribution margin will ________.
◦ increase per unit
◦ stay the same
◦ decrease per unit
◦ cannot be determined from this information