Choose the correct form of the verb.
¿Dónde __________ Marcos? En la clase de español? estoy estás está están
Answer : está
Entire sentence : ¿Dónde está Marcos?
Explanation: The verb "estar" is used to describe the physical location of someone or something. As the subject in this sentence is "Marcos", that is third singular person, the verb must be conjugated in the third singular persona too. Él está.