The best answer to the question "How do different audiences affect acting in theatre?" is:
a. They contribute to the energy, feedback, emotional connection, and cultural context of the performance, inspiring actors and shaping their choices.
This option encompasses the varied ways that different audiences can influence a performance, highlighting the dynamic interaction between actors and the audience that can affect the overall experience of the theatre. While the other options offer valuable perspectives, option a captures the broad impact of the audience on the performance.