One adaptation that is unique to marine mammals is they nurse their young.. The correct option among all the options that are given in the question is the fourth option or the last option or option "d". I hope that this is the answer that you were looking for and the answer has come to your desired help.
Holmes said to Watson "My dear doctor, this is a time for observation, not talk, because it was part of his method to observe closely and then to consider his observations. The correct answer is A.
