The correct answer is C.
If Jason is nervous about giving speeches in front of big crowds, he should practice his speech in front of a mock audience. The mock audience can be his family, his friends or even nobody, just an imaginary group of people. The purpose of this trial speech is to get used to people looking at the speaker so that he wouldn't get so nervous during the real performance. This mock session should be repeated as many times as needed, till he feels he is more confident and ready to deliver his speech in front of a real audience.