Older adults may have difficulty performing activities of daily living due to ______.

Aging causes degenerative changes in cartilage, synovial fluid, and connective tissue, progressively reducing joint range of motion. This reduction directly impairs functional movements required for activities of daily living such as dressing, bathing, bending, and reaching overhead. Decreased joint mobility is one of the most clinically significant contributors to functional decline in older adults.

While older adults do experience a relative increase in type I fiber proportion due to type II fiber atrophy, this shift in fiber composition does not directly restrict the functional movements needed for activities of daily living.

Decreased maximal heart rate is an age-related cardiovascular change that affects aerobic capacity and endurance, not the joint and movement function required for activities of daily living.

This choice is factually incorrect - older adults experience decreased, not increased, muscle elasticity, and even so, elasticity changes are secondary to joint mobility as a cause of functional limitation.