a speaker's interest in a topic corresponds to
the speaker's level of knowledge
the speaker's level of enthusiasm
the speaker's understanding of audience
the audience's interest in the topic

This best corresponds to the speaker's level of enthusiasm about his topic.
A person can know a lot about the topic despite not being interested in it (Visualize, for example, a student forced to make a report on a topic. He would know a lot but would not be interested in it.) The speaker's understanding of the audience, or the audience's own interest, doesn't affect the speaker's own interest.

Ibelieve the correct answer is c.

C. o l percieve myself and sing myeelf