The correct answer to this open question is the following.
Although there are no options attached, we can comment on the following.
The difference in Jules's performance can be explained by the phenomenon of Social Facilitation.
The Social Facilitation theory says that people have the tendency of performing better in contests when they know they are being watched by fans or spectators. This theory tries to explain the behavior of persons in social environments.
That is why when he practiced with his father, he swam at a moderate pace, even though his father goaded him to swim faster. However, when he participated in the swimming competition at school, the attention of the gathered crowd and the presence of other swimmers made him swim faster than he did during practice.
This social pressure made him improve his performance. Jules knew he was in a contest and that he had to overperform his competitors if he did not want to be ridicule to choke under pressure.
