The Research by Natalie De Witt and Michael Sussman Showed

The research by Natalie De Witt and Michael Sussman showed that proton pump AHA3 is localized in the membrane of companion cells of the source tissue.What is the function of this pump?

A) to move protons from inside of a companion cell to outside
B) to move protons from outside of a companion cell to inside
C) to move protons from inside of a companion cell to a source cell
D) to move protons and sucrose from inside of a companion cell to outside
E) to move protons and sucrose from outside of a companion cell to inside