Question

ana y marco ______ sus nombres en la arena.

A) estoy escribiendo

B) estamos escribiendo

C) estan escribiendo

D) estas escribiendo

Answer 1

C) estan escribiendo

estan is the ellos form which means they are so it is Ana and Marcos they are writing their names

Answer 2

Answer:

C) estan escribiendo

Explanation:

In order to complete the sentence, you have to find the right form of the verb estar in present tense and this corresponds to the verb to be in English.  The verb is conjugated as follows:

Yo estoy

Tu estás

El/Ella está

Nosotros estamos

Ustedes están

Ellos están

Then, the sentence refer to Ana y Marco which is they and in Spanish is Ellos. According to this, the right answer is Ana y Marco están escribiendo sus nombres en la arena.