To improve your cardiovascular fitness:

A.

Include a minimum of 20-30 minutes of aerobic activity 3-4 times per week

B.

Use weights or resistance to build your muscles

C.

Perform push ups and curl-ups daily

D.

Stretch every day

C. Perform push ups and curl-ups daily

A. Include a minimum of 20-30 minutes of aerobic activity 3-4 times per week

Explanation:

Your cardiovascular fitness, also called cardiovascular fitness, says a lot about your health and how much other conditions can affect it. Basically, cardiovascular fitness measures how well your body absorbs oxygen and distributes it to your muscles and organs during prolonged periods of exercise. The best way to improve your cardiovascular fitness is through exercise that forces and stimulates the heart to work harder. Aerobic exercise is the best alternative for this.

For this reason, we can say that the best answer to your question is the letter A.