Marcos y Alberto: <u>Vamos</u> a empezar el trabajo dentro de unas horas.
Explanation:
This question is concerned with the conjugation of the verb “ir” in present for the speakers Marcos and Alberto. This verb “ir” an irregular on. Its conjugation according to number and person in the simple present tense is the following:
<em>Yo voy</em>
<em>Tú vas</em>
<em>Él/Ella/Eso van</em>
<em>Ellos van</em>
<em>Nosotros vamos</em>
In the dialogue, Marcos and Alberto tell Bruno about what they are going to do, therefore, the correct verb form that completes the sentence is “Vamos,” which is used for the firs person plural: “Nosotros” (We):
Marcos y Alberto: (Nosotros) Vamos a empezar el trabajo dentro de unas horas.