What are two limitations to the data being returned by the Controller?

A developer wants to call an Apex Server-side Controller from a Lightning Aura Component.

What are two limitations to the data being returned by the Controller? (Choose two.)
A . A custom Apex Class can be returned, but only the values of public instance properties and methods annotated with @AuraEnabled are serialized and returned.
B . Lists of Custom Apex Classes cannot be returned by Apex Controllers called by Lightning Aura Components.
C . Basic data types are supported, but defaults, such as maximum size for a number, are defined by the objects that they map to.
D . Only Basic data types and sObjects are supported as return types for Apex Controllers called by Lightning Aura Components.

Answer: AC