b
Explanation:
I'm apologize if I'm wrong
The part of muscle that he needs to train is the Slow-twitch muscle fibers.
<h3>What are Slow-twitch muscle fibres?</h3>
The Slow-twitch muscle fibers are the muscle fibres that are used to support long distance endurance journey such as the marathon race.
Therefore, the part of muscle that he needs to train is the Slow-twitch muscle fibers.
Learn more about muscle here:
brainly.com/question/13920046
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The right side of your heart receives oxygen-poor blood from your veins and pumps it to your lungs, where it picks up oxygen and gets rid of carbon dioxide. The left side of your heart receives oxygen-rich blood from your lungs and pumps it through your arteries to the rest of your body.
I hope the last word to be *except
B. Increased stress
