Running, swimming, and using an elliptical machine are all ways to improve your:

Muscular Strength

Flexibility

Muscular Endurance

Cardiovascular Endurance

All of the above options are correct. Running, swimming, and using an elliptical machine are all forms of cardiovascular exercise that can improve muscular strength, flexibility, muscular endurance, and cardiovascular endurance.

Running, swimming, and using an elliptical machine are all ways to improve your cardiovascular endurance.