Which factors can limit an individual's flexibility?

The correct choice highlights several key physiological and structural elements that inherently restrict an individual's flexibility. Bony structure refers to the shape and structure of bones, which can determine the limits of joint movement; for instance, the shape of the hip socket can impact how much the leg can rotate. Fat layers can also impede flexibility because additional body fat may restrict muscle movement and joint mobility during exercises. Skin's elasticity and thickness can influence how freely joints can move. Muscles and tendons play a significant role as well; tight muscles can reduce range of motion, while the elasticity of tendons affects how far a muscle can stretch.

In contrast, other factors listed could have a more indirect or secondary role in flexibility. Environmental temperature can affect muscle elasticity temporarily, but it doesn't fundamentally limit flexibility in the same way that structural components do. Hydration and air pressure might influence performance but are not direct limitations on flexibility itself. Cardiovascular endurance, body mass, and aerobic capacity are more related to overall fitness and stamina rather than flexibility. Finally, while age and gender can influence muscle tone and overall flexibility over a lifetime, the structural factors outlined provide a more immediate and precise understanding of what limits flexibility on a physiological level.