Complete the hungry traveler's text message.

We had been driving for four hours straight, so we finally stopped ___ some highly questionable gas station sushi.

The correct answer is to buy.

When the verb "stop" is followed by a to-infinitive, it means pausing one activity in order to do another (stopping in order to buy).

If we used the gerund "buying," it would mean they completely ceased the habit of buying sushi!