What is the purpose of this excerpt?

all of a sudden, i heard ear-piercing screams. my heart stopped beating. like all mothers who from another room hear a child screaming for an unknown reason, i feared the worst. i ran out of the kitchen into the living room, and i stopped short. i could not but laugh at what i saw. my son hung upside down from the couch where his shoe had stuck to the cushion with velcro.

analyze
persuade
entertain
inform

I believe it would be to inform, the particular excerpt isn't really informing about anything, and its not persuading the reader to do anything, simply attempting to entertain the reader with a story.

to give the reader a sense of the chaos, fear, and havoc taking place

the sentence does not violate the phrase structure second rule (introduced by noam chomsky) because noun phrases consist of a determiner such as a, the or every, and a noun. in the sentence, the noun phrase the cake includes a determiner (the) and a noun (cake).

on the other hand, the first rule indicates that a sentence encloses a noun phrase, followed by a verb phrase. the example sentence can be analysed as follows:

john (n) + ate (v) + the (det) + cake (n).