Question

which is a strength - training activity?
sit - ups
tennis
hopscotch
jump roping

Explanation:

Sit - ups are a form of strength - training as they target the abdominal muscles and help build strength in that area. Tennis is more of a sport that combines elements of cardiovascular endurance, hand - eye coordination, and some strength but is not primarily a strength - training activity. Hopscotch is a children's game that mainly involves balance and some basic movement skills rather than strength - training. Jump roping is a cardiovascular exercise that improves heart and lung function and also has some elements of coordination but is not a strength - training activity.

Answer:

sit - ups