Answer:
A. The products' contribution margin per unit of constraint
Step-by-step explanation:
When resources are constrained, the products' contribution margin per unit of constraint should be used to guide product mix decisions.
A product mix is referred to the the entire range of products that is offered by a company.
The products' contribution margin per unit of constraint is the contribution margin per unit which is divided by the units of resources that are constrained in order for the production of one unit.