Flexibility is best described as

• A. The speed at which a person can perform tasks.
• B. The range of motion in joints.
• C. The body's ability to use oxygen.
• D. Degree to which an individual muscle will lengthen.

Answer: (D)

Flexibility is the ability of muscles and connective tissues to lengthen so joints can move through a wide range. Describing it as the degree to which a muscle will lengthen directly captures this tissue extensibility—the more a muscle can lengthen, the more movement at the joint is possible, and thus the greater the flexibility. Other options describe different fitness aspects: speed is about how fast tasks can be done, oxygen use relates to aerobic fitness, and the range of motion describes the outcome but not the underlying tissue lengthening capability. So focusing on how much a muscle can lengthen explains what enables that usable range of motion.