As a part of his workout regimen, a 21-year-old college football player often engages in squats and lateral arm holds. these are examples of what type of exercise?
a) aerobicb) isotonicc) anaerobicd) isometric

The correct answer is- isometric exercise

Explanation:

Isometric exercise also called static strength training which requires contraction of a particular muscle group. In isometric exercise, the joints do not move and the length of the muscle does not change noticeably.

Squat and lateral arm hold are the example of isometric exercise. Isometric exercise improves the strength of a particular muscle or group muscle for example squat helps in building leg muscles.  

Therefore if a girl is engaged in squats and lateral arm holds then it is an example of isometric exercise.