Functions of a cell as well as a human body depend on the activity of the membrane transporters, functional deterioration of these transporters can lead to diseases. In these cases, drugs are given to stimulate or inhibit these transporters.

Membrane transporters are classified depending on how they transport substances, number of substances transported and direction of transport.

Which category do the following membrane transporters belong to?

Each option may be chosen once, more than once, or not at all.