Answer:
a. Me gusta(n) esta(n) _____. Voy a comprar un.
b. ¿Vas a comprar el (la) _____ o el (la) _____?
c. Yo voy a comprar el (la) _____
Step-by-step explanation:
For the first one, it would be "me gusta esta" if you're talking about something singular ("I like this"). For example:
I like this apple -> Me gusta esta manzana
However, if you're talking about a plural object, it would be "me gustan estan." For example:
I like these apples -> Me gustan estan manzanas
For the second and the third ones, the article you use (el or la) depends on the gender of the object. If it is masculine, use el (the masculine article). If it is feminine, use la (the feminine article).