Solution: Choice C is correct.

Out-of-pocket expenses are the expenses paid by the client.

Now, client has to pay 20% of the insured expenses above 250 Dollars and a fixed expense of first 250 Dollars.

Therefore, if the total expenses insured are x (paid by client and insurance company both)

Then expenses paid by the client will be 20% (x-250) + 250.

Also, it is given that the client has not reached out-of-pocket maximum which is 5000.

Therefore, 20% (x-250) + 250 < 5000

Or 20% (x-250) < 4750

Or .2 (x-250) < 4750

Or x-250 < 23750

Or x < 24000.