Aaron Has Been Training to Run His First Half Marathon

Aaron has been training to run his first half marathon and has timed himself repeatedly over the past months.When he actually runs the half,he is surprised that he performs

A) more poorly than he expected,because he is distracted by the other people running with him.
B) more poorly than he expected,because he hasn't prepared himself to deal with the changes created in the air around him by the other runners.
C) better than usual,due to the mere presence of the other runners.
D) without being affected in any way by the other runners.