The Black-Scholes-Merton Model's Implied Volatility Is

The Black-Scholes-Merton model's implied volatility is:

A) the market's estimate of the future value of the stock's random volatility over the option's life
B) the volatility that equates the BSM model price to the market price,if all other inputs are known
C) the market's estimate of the future value of the stock's random volatility over an infinitesimal time interval
D) the market's estimate of the stock's random volatility over an infinitesimal time interval beginning when the option matures
E) another name for estimating the volatility using historical stock price data