During a nature documentary, Aman learned that whales have a slow heartbeat,
especially when they dive deep underwater. Why might a whale’s heartbeat slow down
during a deep dive?

Answer: B. To save oxygen while underwater

Whales hold their breath during a deep dive. Slowing the heartbeat reduces how fast the body uses up its stored oxygen, so the whale can stay underwater longer. It does not help it swim faster or make bubbles.

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