The correct answer is D. no article.
The word “a” is used before singular nouns that refer to something that is not specific. The word “an” is used before singular nouns that begin with a vowel sound. The word “the” is used before singular nouns that refer to something specific. In this case, the woman is wearing an awful hat, but we do not know which hat she is wearing. Therefore, we do not need to use an article.
Here are some examples of when you would use an article:
- I saw a woman wearing a hat.
- I saw an owl flying in the sky.
- I saw the Eiffel Tower in Paris.
In these examples, the woman, the owl, and the Eiffel Tower are all specific things. We know which woman, owl, and Eiffel Tower we are talking about. Therefore, we need to use an article.
However, in the example “This woman is wearing an awful hat,” we do not know which hat the woman is wearing. Therefore, we do not need to use an article.