The correct answer is: B. expected rate of return
The expected rate of return is the weighted average of the possible returns, where the weights are the probabilities of the returns occurring. It is a measure of the average return that an investor can expect to earn on an investment over a given period of time.
The average rate of return is simply the sum of the returns divided by the number of returns. It does not take into account the probability of each return occurring, so it is not as accurate a measure of the expected return as the expected rate of return.
The past rate of return is the return that an investment has actually earned in the past. It is not a reliable predictor of future returns, as past performance is not necessarily indicative of future results.
The weighted rate of return is the weighted average of the returns of a portfolio of investments, where the weights are the proportions of the portfolio invested in each asset. It is a measure of the average return that an investor can expect to earn on a portfolio of investments over a given period of time.