A cell biologist working with cultured cells from intestinal epithelium finds that the cells take up glucose from the growth medium 10 times faster when the glucose concentration is 5 mM than when it is 0.2 mM. She also finds that glucose uptake requires Na+ in the growth medium. What can you say about the glucose transporter in these cells?

-The transporter is a Na+-glucose symporter with a K greater than 0.2 mM.
-The transporter is a Na+-glucose antiporter with a K less than 0.2 mM.
-The transporter is a Na+-glucose antiporter with a K greater than 0.2 mM.
-The transporter is a Na+-glucose symporter with a K less than 0.2 mM.