Which of the following best pairs each exercise type with the primary fitness component it most directly improves?

Stretching — musculoskeletal fitness; Aerobic exercise — body composition; Resistance training — flexibility, since strength work can increase range of motion when executed through full joint angles over long periods.

Aerobic exercise — cardiorespiratory fitness; Resistance training — musculoskeletal fitness; Stretching — flexibility.

Resistance training — cardiorespiratory fitness; Stretching — body composition; Aerobic exercise — flexibility, because prolonged movement increases muscle length over time which then alters composition slowly.

Aerobic exercise — flexibility; Resistance training — body composition; Stretching — cardiorespiratory fitness, reflecting that active stretching can sometimes raise heart rate moderately.