What is defined as a series of uniform payments made at equal intervals of time?

An annuity is defined as a series of uniform payments made at equal intervals of time. It represents a financial product where a set amount of money is paid at regular intervals, typically on an annual or semiannual basis. This definition highlights the key characteristics of an annuity, including the consistency of payment amounts and the regularity of their occurrence.

Annuities are commonly used in various financial contexts, such as retirement planning, where individuals might receive regular payments over a specified period as a way to provide a stable income after they stop working. The term specifically captures the notion of time-based, equal payments that can be contrasted with other financial instruments.

In this context, it can be distinguished from the other options such as perpetuity, which refers to a series of cash flows that continues indefinitely, and does not imply any finite duration for payments. The annual rate typically refers to an interest rate expressed on an annual basis, not a series of payments. Regular rate is a more ambiguous term that doesn't specifically define a payment structure.

Thus, the concept of an annuity encompasses the critical aspects of regular, uniform cash flows over specific intervals, making it the correct choice in this context.