Question

—¿dónde están uds.? —nosotros ______ en la clase de ciencias naturales.
\testa\t\t\t\testan
\testoy\t\t\t\testamos

Explanation:

The sentence uses the first-person plural subject "Nosotros" (We). The correct present tense conjugation of the verb "estar" (to be) for this subject is "estamos". The other options do not match: "esta" is third-person singular feminine, "estan" is a misspelled third-person plural, and "estoy" is first-person singular.

Answer:

estamos