Answer
C.
Work Step by Step
Myoglobin supplements oxygen levels when there is hypoxic stress, and this system is especially well developed in marine mammals to allow for long, deep dives.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.