What types of migration are supported from 32-bit to 64-bit?

Volume SnapMirror operates at the physical block level. It replicates the contents of an entire volume, including all Snapshot copies, plus all volume attributes verbatim from a source (primary) volume to a target (secondary) volume. Implicitly, the destination volume will be the same as the source volume. Since C is incorrect, A & B must be correct.

Qtree snapmirror operates at the logical level, so it is unimportant that the destination system has a different volume configuration.

ndmpcopy is similarly operating with data already read from the volume and so the destination volume type is not a consideration.