To maximize profit when there is a single resource constraint $($e$.$g$.,$ machine hours$)$ and excess demand for each of a multiple set of outputs that could be produced by a firm, the short$-$term product mix should be determined $\_\_\_\_\_\_.$

Multiple choice question.

by ranking products based on their respective gross profit per unit

based on the relative resource consumption of each product

on the basis of the relative sales values of each of the products

by ranking products based on their contribution margin per unit of the scarce resource