If the Price of a Company's Stock Truly Reflects the Value

If the price of a company's stock truly reflects the value of a share in the company, then

A) it is impossible for the stock price to change by 20% in a single day, as in 1987.
B) it is impossible for the stock price to increase by 84% within a single year, as in 1999.
C) stock prices can only change abruptly when accounting scandals are uncovered, as in 2002.
D) abrupt stock price changes reflect abrupt changes in the public's perception of fundamentals and risk.