Answer
b. a transmembrane protein
Work Step by Step
The $Na^{+}$-$K^{+}$ pump is a transmembrane protein.
Transmembrane proteins are located on both sides of the cell membrane and transport particles through the cell membrane.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.