Answer:
C
Step-by-step explanation:
Any dish that has a crust and filling is considered a pie. it does not have to be flour-based at all.
For A: Mash potatoes do not really serve as a crust for the pie.
For B: This is not true as there are several dishes that use this method but aren't considered pies. For example, some refer to shepherd's pie as a British casserole.
For D: Also false as most savory dishes are not considered pies at all.