How is skeletal maturity typically assessed?

Skeletal maturity is primarily assessed through the measurement of bones, particularly in the hand and wrist, which provides critical insights into an individual's growth and development stages. X-ray imaging is often used for this purpose, analyzing specific growth plates and bone structures to determine the extent of maturation.

Weight and height for age are additional factors that help contextualize skeletal maturity in relation to normative growth patterns, though they do not directly measure skeletal development. This combined approach allows for an accurate assessment of skeletal age compared to chronological age.

The other options, while related to physical fitness and health, do not specifically address skeletal maturity. Heart rate variability assesses cardiovascular health, physical flexibility tests measure range of motion, and strength assessments focus on muscular capability. None of these directly evaluates the maturation of skeletal structures, which is the core focus of the correct answer.