Explanation/Reference:
Shared member hierarchy is also an alternate hierarchy. All shared member refers to stored members of outline (C). In aggregate storage application only multiple hierarchies can have shared members. (A) Stored hierarchy has only addition as consolidation operator. You can use the stored hierarchy type where aggregation is the only mathematical requirement. If you have some shared member in hierarchy then use multiple hierarchy.
Incorrect answers:
B: An outline dimension in an ASO database can have any number of members and these members can only be set as either stored members or dynamic members. They can even have both of the hierarchies. In order to set the dimension to have both types of hierarchies, you need to enable Multiple Hierarchies Enabled.