A simple subject is probably the most basic unit in sentence construction. A subject is a noun, which is a person, place, thing, or idea. A subject tells us who or what the sentence is going to be about. Without a subject, we cannot have a complete sentence. A simple subject is a subject that has just one noun as the focus of the sentence. This means that only one noun does the action, or connects, to the verb of the sentence.
The answer is simile because similes uses the word as
example: That man ran as fast as a roadrunner.
Answer:
The boy is walking down the street holding is mother's hand while singing a funny little song.
Explanation: