Final answer:
The most likely memoir among the options is 'Over the Big Top: My Year in Circus Training' because it indicates a personal account of someone's experiences in circus training, a common element of memoirs.
Step-by-step explanation:
A memoir is a written factual account of somebody's life, typically from a personal perspective, often focusing on the author's personal experiences and significant events in the author's life. Given the options listed, A. Over the Big Top: My Year in Circus Training is most likely a memoir.
The reason is that the title suggests a personal account (My Year) of a specific period in someone's life spent training in the circus. This is in contrast to the other titles that suggest a more general historical, cultural, or report-style perspective, which would be less likely to contain the personal reflections and experiences characteristic of a memoir.