<h3>I am going to see my friends at the stadium. </h3>
Answer: A. Voy a ver a mis amigos en el estadio.
Explanation: The other options are incorrect. B) incomplete because the "a" preposition, that indicates who is going to see, is missing. C) incomplete because is the preposition "a" that is part of the verbal expression "ir a ver" to describe plans is missing. D) incorrect tense because the verb "veo" is in the present, but when you describe plans with the verbal expression "ir a ver" the verb "ver" must be in the infinitive.