The principle of specificity is best illustrated by which of the following? (A) Lifting heavy weights to increase aerobic performance (B) Power walking to improve arm strength (C) Doing push-ups to reduce waistline size (D) Doing sit-ups to increase abdominal strength - HSC - SSCE Personal Development and Physical Education - Question 12 - 2001 - Paper 1

The principle of specificity refers to the idea that training should be relevant and appropriate to the sports or fitness goals of the individual. In this case, option (D) is the best answer because doing sit-ups directly targets the abdominal muscles, thus specifically increasing abdominal strength.

Other options, such as lifting heavy weights or power walking, do not specifically focus on strengthening the core muscles. While push-ups can help in building upper body strength, they do not address waistline reduction specifically. Therefore, the most relevant example that illustrates the principle of specificity is option (D).