I believe it is B, some of the other answers are applicable, but just because it has those, doesn't mean it is a complete sentence. A sentence may express more than 1 thought, or it may not, but you cannot say that only 1 of those is true, therefore, A and E are wrong, but can be true in certain sentences. C and D deal with the punctuation and capitalization. Although these are important to making a complete sentence, one wouldn't say that any sentence with capitalization and punctuation is classified as a complete sentence. I complete sentence needs both punctuation and capitalization, however, it would be best classified as a sentence that has a subject and a verb/predicate.
