Answer:
Omar and Eric = They
Ms. Monroe = She
The bicycle = It
Keiko and I = We
Step-by-step explanation:
I'm basing my answer off of what I assume to be the underlined nouns, since the underlines aren't actually visible.
"Omar and Eric are training for a marathon." is spoken in third person, and thus you would assume that the narrator is neither Omar nor Eric, making the pronoun "they". In addition, Omar and Eric together are two people, making the subjects of this sentence plural. Thus, you would use "they".
"Ms. Monroe will meet with the students after school." Ms. Monroe is a woman based off of her title, and because the subject of this sentence is singular, we would use "she".
"The bicycle belongs to Trina." This sentence's subject is an object- the bicycle. The sentence only talks about one bicycle, and thus you would use "it" as the pronoun.
"Keiko and I are hoping to win first prize at the science fair." This sentence is spoken in first person, and because of this the pronoun must also be in first person. So, you would use "we" to describe the narrator and Keiko.