Answer:
a.) Require all project resources to work overtime
Step-by-step explanation:
If a project manager requires all project resources to work overtime, he or she is not reducing overload among project resources, but actually increasing it, with the potential negative implications that his action may entail.
The other three methods or tactics described in the question are conductive to reducing work overload, either by reordering tasks (numerals a and b), or by including more workers in the project (numeral c).