Answer: Yo soy optimista
I am optimistic
Explanation: The subject in this sentence is "Yo", that is a first-person in the singular, so the verb must be conjugated in this form. Yo soy.

"I do not feel well enough to go to school today, my throat hurts, my nose has been dripping all day and I have not stopped sneezing, I think I can have a cold"
Are you asking for a translation..? If so it's "Choose the words that are argentinismos."