Answer:
Went.
Step-by-step explanation:
This question is simply about using the most appropriate verb to fill the gap and make the sentence complete and logical.
A verb can be defined as a doing word or a word that describes an action being performed by someone or something. Some examples of verbs are go, come, dance, went, sit, walk, clap, etc.
We cannot use go in the sentence because the action has been performed already. Therefore, we would use the past tense of go which is went.
I went to the supermarket to buy some coffee.