Question

the function of the cftr receptor is to move chloride ions out of a cell by active transport. this is an example of
a reaction coupled with the production of atp.
an oxidation reaction.
a reduction reaction.
a reaction requiring the input (use) of energy (atp).
equilibrium.

Explanation:

Active transport (like CFTR moving chloride ions) requires energy (ATP) because it moves substances against their concentration gradient. Oxidation/reduction involve electron transfer, ATP production is for energy - making (not using in active transport here), and equilibrium is a balanced state, not related to active transport's energy need. So the correct option is the one about requiring ATP input.

Answer:

D. a reaction requiring the input (use) of energy (ATP)