Answer :
Answer: e. the lowest variable cost per unit that can reasonably be expected.
Explanation:
The lowest variable cost per unit that can reasonably be expected will be used in the computation of the best-case analysis of a project.
It should be noted that the lower variable costs will tend to increase the profit of a company under the best case analysis and therefore when it's being compared with other options, it's the correct option.
Therefore, the correct option is E.