An individual purchased an annuity with a series of premium payments continuing over a period...

Understanding annuity phases.

An annuity has two primary phases:

Accumulation period: when premiums are paid and values grow.

Annuity (liquidation) period: when income payments are received.

Apply the facts.

The question describes premium payments being made over time.

No income distributions are occurring yet.

Why the other options are incorrect.

Liquidation / annuity period involves payouts, not payments.

Period certain describes a payout guarantee, not a payment phase.

Conclusion.

Premium payments are made during the accumulation period.