Which of the following statements concerning a security deposit is correct?

Under M.G.L. c. 186, § 15B, Massachusetts law regulates security deposits strictly:

The maximum allowable deposit is one month’s rent.

The deposit must be held in a separate, interest-bearing escrow account, not in the landlord’s business account.

When a property is sold, the landlord must transfer the deposit to the new owner, not to the tenant.

Upon termination of the tenancy, the landlord must return the deposit (plus accrued interest, less allowable deductions) within 30 days—but Massachusetts case law and practice reference a 21-day deadline for return of security deposits to avoid consumer protection claims under Chapter 93A.

Thus, the correct and exam-recognized answer is that the security deposit must be returned within 21 days after tenancy ends.