Robert owns . . . . . . . . yellow and . . . . . . . . blue bird. A. a, a B. the, the C. a, no article D. a, the

The correct answer is: A. a, a

The article “a” is used before singular nouns that are not specific. In this case, we do not know which yellow bird or which blue bird Robert owns, so we use the indefinite article “a”.

The article “the” is used before singular nouns that are specific. For example, if we said “Robert owns the yellow bird that sings all day long”, we would be referring to a specific yellow bird.

The article “no article” is used before plural nouns. For example, if we said “Robert owns birds”, we would not be referring to any specific birds.

In this case, we are not referring to any specific yellow bird or blue bird, so we use the indefinite article “a” before each noun.