The correct answer is B,C,E.
Why these three:

B. Custom picklist fields can be either controlling or dependent fields – True. A custom picklist has the flexibility to serve as either the controlling field or the dependent field in a field dependency relationship.
C. Multi-select picklist can be a dependent field but not a controlling field – True. Multi-select picklists are only supported as dependent fields; they cannot be used as controlling fields.
E. Checkbox fields can be controlling fields but not dependent fields – True. Checkboxes are valid as controlling fields (with just two possible values: checked/unchecked), but they cannot be set up as dependent fields — only picklist or multi-select picklist fields can be dependent.

Why not the others:

A. Import wizard only allows import into dependent picklist if values match controlling field – False. In reality, the Data Import Wizard and Data Loader do not enforce field dependency validation — you can import mismatched combinations that wouldn't be selectable through the UI, since dependency rules aren't checked during import.
D. Standard and custom picklist fields can be dependent fields – False. Only custom picklist fields can be used as dependent fields. Standard picklist fields can only serve as controlling fields, not dependent ones....