Which of the following are NOT true

a.

Risk-neutral valuation is flawed because the assumption that investors are risk-neutral is unrealistic.

b.

Risk-neutral valuation involves assuming that the expected return is the risk-free rate and then discounting expected payoffs at the risk-free rate

c.

In a multi-period binomial tree using the Cox-Ross-Rubinstein method, the risk neutral probabilities change between the periods.

d.

Risk-neutral valuation and no-arbitrage arguments give the same option prices