"I" is the one word among the following choices given in the question that represents the <span>subject of this sentence. The correct option among all the options that are given in the question is the fourth option or option "d". I hope that this is the answer that has actually come to your desired help.</span>
The correct answer is Carol has a cottage near the shore.
This supporting detail has nothing to do with her study of marine life. She could have this cottage because she inherited it, or she just likes the place - it doesn't really contribute to her love or study of marine life. The other options clearly support why she is studying marine life, whereas the one with the cottage does not.
