Answer: c. looked / was searching
Explanation:
When I first got off the plane, I looked around as if in a fog. I was searching for my classmates.
The sentence started with the past tense being used by the narrator. As such, the rest of the narration has to be in past tense as well.
With this in mind, the word looked and the phrase was searching would be the right words to use to fill in the blanks.
