The correct answer is indirect reference.
B. indirect reference
The correct answer is (B) Indirect or implied reference; a casual or passing reference; an indiscreet or incidental mention of something. Also, a covert reference, a metaphor, or a parable.
Allusion comes from Latin allusio.
Examples of use:
- He made an allusion to the school's flagging work ethic during his address.
- The musician's allusion to the conductor was very complimentary.