Final answer:
The only complete sentence among the options is d, 'The landscape of deep blue lakes tells the story of ancient glacial action,' because it includes both a subject and a verb and expresses a complete thought.
Step-by-step explanation:
The student asks which option represents a complete sentence. A complete sentence must have a subject and a verb, and present a complete thought. Option d is the correct answer: "The landscape of deep blue lakes tells the story of ancient glacial action." This sentence contains a subject (the landscape of deep blue lakes) and a verb (tells) and communicates a complete thought.
Options a, b, and c are all fragments because they are missing either a subject or a verb, or they don't express a complete thought. Option b seems to begin a subordinate clause and option a does not contain a verb connecting the subject to the rest of the sentence. Option c has a subject and a verb, but it doesn't present a complete thought. It describes a lake but doesn't have the main clause.