2. The spectators/audience cheer the tennis players on at Wimbledon. 3. About 40,000 competitors/rowers run in the London Marathon each year.

2. Spectators is the correct choice: it means people watching an event. The audience usually refers to people watching or listening to a performance or broadcast.

3. Competitors is the correct choice: the marathon participants are runners competing in the event. Rowers are people who row boats.