Which of the Following Statements Is Most Likely True of a Protein

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

A) Sodium and glucose compete for the same binding site in the cotransporter.
B) Glucose entering the cell down its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient.
C) Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell.
D) A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.