The correct answer is D. no article.
The reason is that the name of the hotel is not known to the speaker. If the speaker knew the name of the hotel, they would have used an article. For example, they might have said “We stayed at a very nice hotel called the Ritz-Carlton.”
However, because the speaker does not know the name of the hotel, they use no article. This is because articles are used to identify specific nouns. When the speaker does not know the name of the hotel, they cannot identify it specifically, so they do not use an article.
The other options are incorrect because they all use articles. A and an are indefinite articles, which are used to refer to general or unspecified nouns. The is a definite article, which is used to refer to specific or particular nouns. In this case, the speaker is not referring to a general or specific hotel, so they do not use an indefinite or definite article.