Answer:
Van
Explanation:
Van refers to both the Aunt and Uncle as "they", they go to the mountains. All the other forms of ir refer to either I, he/she, you, we, etc.
I like to write A mi te gusta escribir
I like writing A mi me gusta escribir
You like to write A ti te gusta escribir
You like to write A ti le gustan escribir
"participaban" should be in the blank.
