Read the sentence. the photographs had become brittle with age. what is the simple subject?

Photographs.

Explanation: the subject of a sentence is the person or thing that performs the action of the verb. The simple subject is the main word or words in a subject, without incluiding any modifiers. In the given sentence, the verb is "had become" the subject that performs the action of the verb is "The photographs" but the simple subject doesn't include modifiers (like "the") so it is just "photographs."