Which of the following statements is correct for the Black$-$Scholes partial differential equation $($pde$)?$

To derive the Black$-$Scholes pde, you set up a risk$-$free portfolio $($consisting of the option and the underlying asset$)$ that earns the market risk premium.

The Black$-$Scholes price of a European put option decreases as the expected return required by investors from the underlying stock increases.

Any set of risk preferences can be used in order to solve the Black$-$Scholes pde and get an option price.

The Black$-$Scholes pde is dependent on risk preferences because it only involves the risk$-$free rate and NOT the expected return on the underlying asset.