Neo wants disability insurance in order to protect his income in casehe is injured and unable to work. Neo has a friend who sustained an extended disability and found it difficult near the end of the benefit period because she felt that the fixed monthly benefit she was receiving was not able to purchase the same amount of goods as when she first started receiving the income. Neo asks his insurance agent, Moustafa, if there is anything that can be added to the policy to ensure that this would not happen to him. Which of the following would be the CORRECT option that would address Neo's objective?

a) add a cost of living adjustment

b) add a future purchase option

c) add a return of premium feature

d) add a premium rating rider