Answer:
A. You can sublet your apartment once to anyone as long as you tell the landlord.
Explanation:
A sublet, or sublease agreement, adds someone new to an existing lease. Usually the new person (subletter) replaces someone who is moving out (sublessor or sublessee) but it can also happen with any new person being added to a lease.
Hence, the statement that is true about subletting is:
A. You can sublet your apartment once to anyone as long as you tell the landlord.