In internal rate of returns, discount rate which forces net present values to become zero is classified as

positive rate of return
negative rate of return
external rate of return
internal rate of return

The correct answer is: D. internal rate of return

The internal rate of return (IRR) is the discount rate that makes the net present value (NPV) of an investment equal to zero. It is a measure of the profitability of an investment, and it is used to compare different investment options.

A positive IRR indicates that an investment is profitable, while a negative IRR indicates that an investment is not profitable. The IRR is often used as a decision-making tool, and it is considered to be one of the most important financial ratios.

A positive rate of return is a rate of return that is greater than zero. This means that an investment is expected to generate a profit. A negative rate of return is a rate of return that is less than zero. This means that an investment is expected to lose money.

An external rate of return is a rate of return that is based on the market conditions. This means that it is the rate of return that an investor would expect to earn on an investment in the market.

The internal rate of return is a rate of return that is based on the cash flows of an investment. This means that it is the rate of return that an investor would expect to earn on an investment based on the cash flows that the investment is expected to generate.