Verified Answer :

Allusion means reference of letter c.  Allusion is defined as a spontaneous reference
to a person, place or even an event.  It
could also be used in the term alluding which mean the act of making a
reference to something.  To use allusion
in a sentence can be as follows:  The
technique he used in the tournament is an allusion to karate. It is best used
when you want to make references.  It is
an alternative to the word reference.