An eight-year-old boy dramatically increased his upper body strength after following a six month resistance training program. Which of the following is most likely responsible for this gain? A. Increased number of muscle fibers
B. Enhanced cross-sectional area
C. Greater muscle density
D. Improved neuromuscular functioning

Drag each tile to the correct box. the body monitors the levels of oxygen in the blood to regulate breathing. isabel is running in a marathon and is near the finish line. she feels out of breath. how will her nervous system work to generate a reaction? arrange the tiles in chronological order. isabel's breathing rate increases. sensory receptors in the arteries detect low oxygen levels. the brain sends signals through motor neurons. sensory neurons generate an impulse. the central nervous system relays an impulse to certain brain regions.