Question

How would you tell someone in Mexico that you are going shopping at an open-air market?

Answer 1

Hi,

The answer is 

The question tells us that "you" are going to do shopping, so we want to say " I am going..." and can start with finding the form for "I am going" - yo (I) voy (voy is first person singular of "ir" to go). 

And this is already enough to answer the question, as there is only one option with "voy"  - so the correct answer is: 
C) Voy de compras al tianguis

Hoped I Helped

Answer 2

C) will be your answer hope this helps. :)