People take up hobbies because these activities offer enjoyment, friendship, knowledge, and relaxation. Sometimes they even produce financial profit. Hobbies help people relax after periods of hard work, and provide a balance between work and play. Hobbies also offer interesting activities for persons who have retired. Anyone, rich or poor, old or young, sick or well, can follow a satisfying hobby, regardless of his age, position, or income.
At what time can a person have his hobby？
(13)

A. In his spare time.
B. In his work time.
C. In his workday.
D. In his summer.