1. Correct answer:
b. es
One of the main uses of the verb ser is to talk about the origin of a person or thing. In this sentence, we affirm that Clara is from Paraguay. Therefore, es is the conjugation of the verb ser that matches the third person singular in the simple present. This is so because we can replace Clara by ella. Finally:
Clara es de Paraguay
2. Correct answer:
a. estás
Here in this sentence, we use the verb estar as location because here I'm asking if you are in a certain place (Asunción). So estás is the conjugation of the verb estar for the second person singular in the simple present. This person is tú, which is the formal form of the English subject pronoun you. Finally:
¿Estás tú en Asunción?
3. Correct answer:
c. somos
Somos comes from the verb ser and is the conjugation of this verb for the first person plural in the simple present. This person is nosotros that translates into we in English. So we use the verb ser here because we are talking about a physical description of a person. Finally:
Nosotros somos altos
4. Correct answer:
a. están.
This sentence stands for an emotion, that is, it expresses what a person (or people) is feeling at a certain moment, so we must use the verb estar. So the pronoun here is ellos that translates into they in English. In this way, están is the conjugation of the verb estar for the third person plural in the simple present. Finally:
Ellos están cansados