What’s the definition of the base circle for a cam mechanism?

A、Thebiggestcirclecanbedrawntothecamtheoreticalprofilefromcamrotationcenter;
B、Thesmallestcirclecanbedrawntothecamtheoreticalprofilefromcamrotationcenter;
C、Thebiggestcirclecanbedrawntothecamactualprofilefromcamrotationcenter;
D、Thesmallestcirclecanbedrawntothecamactualprofilefromcamrotationcenter