29. Helen bought an installment refund life annuity for $100,000 under which she received an annual periodic payment of $10,000. If her life expectancy was 15 years at the time she bought the contract, but she lived for 30 years, when would her periodic payments end? a. at the end of her life b. at the end of 10 years c. at the end of 5 years d. at the end of 15 years