Re: test time
That's half of it. The question (incorrectly) asserts that the EGC and phase conductors must be the same size. They do not.
But the concept of "minimum size" goes one way, and not the other. For example, we are allowed to use a #10 EGC and #12 phase conductors in a 20 amp branch circuit. But we are not allowed to use #12 EGC and #10 phase conductors in a 20 amp branch circuit. The NEC Article (not Table) that prohibits that is 250.122(B).