The correct answer is D. no article.
The word “meal” is a non-count noun, which means it does not have a plural form and does not take a determiner (such as a, an, or the) unless it is modified by a word that specifies the type of meal (e.g., a breakfast meal, a dinner meal). In the sentence “We ate a wonderful meal yesterday,” the word “meal” is not modified by any other words, so it does not take an article.
The word “a” is used before singular count nouns that refer to a specific person, place, thing, or idea that has not been mentioned before. In the sentence “We ate a wonderful meal yesterday,” the word “meal” is not modified by any other words, so it does not refer to a specific meal.
The word “an” is used before singular count nouns that begin with a vowel sound. In the sentence “We ate a wonderful meal yesterday,” the word “meal” does not begin with a vowel sound, so it does not take the article “an.”
The word “the” is used before singular or plural count nouns that refer to a specific person, place, thing, or idea that has been mentioned before. In the sentence “We ate a wonderful meal yesterday,” the word “meal” is not modified by any other words, so it does not refer to a specific meal.