ATP is most likely being used for 1.
substance A to enter the cell
2
.
substance B to enter the cell
3.
both substances to enter the cell
4.
neither substance to enter the cell

According to the diagram, ATP is most likely being used for  substance A to enter the cell.

Explanation:

ATP is necessary for the transport of substances against their concentration gradient, participating in the active transmembrane transport.

In the diagram (see picture) substance A has a higher intracellular concentration, and a lower one in the extracellular space. For this substance to enter the cell it is necessary to use an active transport that requires ATP, in order to pass against its gradient.

With respect to the other options: