How does muscle hypertrophy occur?

Muscle hypertrophy occurs primarily through muscle fiber repair and growth as a response to the stress placed on muscles during resistance training. When you engage in exercises, particularly those involving lifting weights or resistance, the muscle fibers experience small tears, known as microtraumas. This damage triggers the body's repair mechanisms, leading to an increase in the size and number of muscle fibers to better handle the stress in the future. This process is facilitated by various factors, including protein synthesis, hormones, and overall nutrition.

The other options do not accurately describe how muscle hypertrophy is achieved. Simply increasing caloric intake can support muscle growth if combined with proper training, but it is not the sole factor for hypertrophy. Avoiding resistance training would not promote muscle growth; in fact, it would likely lead to muscle atrophy due to lack of stimulus. Aerobic exercises, while beneficial for cardiovascular health and endurance, do not significantly contribute to muscle hypertrophy compared to strength training. Hence, the correct answer focuses on the physiological response to the stress of resistance training, which leads to muscle repair and growth.