Question

when working on flexibility, you can evaluate performance improvements by evaluating your body mass index and tracking your daily nutritional intake measuring how long you can hold a specific stretch or how far you can go with the stretch monitoring how long you can sustain an activity or how quickly you can complete a specific distance tracking increases in the amount of weight you can lift or the number of repetitions you can perform

Explanation:

Flexibility is related to the range of motion in joints. Measuring how long one can hold a stretch or how far one can go with a stretch directly assesses flexibility. Body mass index and nutrition (first option) relate to body composition and diet. Sustaining an activity or completing a distance (third option) is about endurance. Lifting weight or repetitions (fourth option) is about strength.

Answer:

measuring how long you can hold a specific stretch or how far you can go with the stretch