he word "baby" is a noun because it represents a person. Nouns are words that name people, places, things, or ideas. "Was" is a helping verb. "Crying" is a verb showing action. "In" is a preposition indicating position. Another noun in the sentence is "crib," but since the question asks for one noun, "baby" is the correct answer. Understanding nouns is fundamental in grammar as it helps in sentence construction and comprehension.