In which of the following scenarios are delivery and noise most likely the primary concerns of the speaker

a.
sheree has been asked to speak about social security to a mixed group of college students, business people, and senior citizens.
b.
erin is giving a motivational speech to a very large group of high school students seated on bleachers in the school’s gymnasium.
c.
charles has been invited to mrs. delaney’s classroom to speak to her elementary school children about fire safety.
d.
ethan is giving a highly technical presentation on biomedical engineering involving several working models, computerized graphs, and video clips to a group of doctors, scientists, and engineers.