The Above Diagram Shows Four Different Types of Transport Proteins

The above diagram shows four different types of transport proteins in the membranes of epithelial cells that line the small intestine. What protein most likely carries out coupled transport of both Na⁺ and glucose in the overall process of glucose absorption?

A) 1 (purple)
B) 2 (yellow)
C) 3 (blue)
D) 4 (green)
E) none of the above