Can, could, or be able to in a B1 question [closed]

Technically, the answer is "could" because we are dealing with a conditional in "as long as". Though many native speakers might say "can".

"Can" is probably allowable, depending on which grammar style or curriculum you consult. But, "could" is the "best" answer because it is most clear and uniquely fitting with the conditional. But, there is one more thing to consider in choosing "could"...

"Could" is used for conditionals that are once removed from our reality. With "could", either the condition is not yet met, can't be met, needs to be met only once, or something else of the sort. By contrast, "can" indicates an ongoing ability empowered by an ongoing condition being met. For example:

I can drive early in the morning as long as I drink my coffee.

That would indicate an ongoing condition that is met every day the speaker drives.

But, "driving lessons" happen once, then are finished. Under normal circumstances, no one would need to continuously be enrolled in a driving school in order to be able to drive, neither in skill nor in law. The sentence doesn't indicate that these circumstances are not normal, so we should presume normal circumstances.

So, the one-event condition modal "could" should be the "best" answer.

(As a final note, we don't know what B1 is, unless you specify "MCERL B1" or "Aptis B1". But, it wouldn't change the answer for normal English, so I just overlooked that part of the question.)