When applying the Capital Asset Pricing Model to the real world, all of the following questions remain to be answered EXCEPT:

What is the best proxy for the market portfolio?

What happens when investors cannot borrow and lend at the risk-free rate?

How good the Capital Asset Pricing Model is at forecasting?

What the Beta of the market portfolio of risky assets is?

What the stability of individual stock betas is?

According to the CAPM, as the number of assets in a portfolio increases, the amount of unsystematic risk in the portfolio:

Remains constant

Decreases

Increases

Changes but in an unknown way

None of the above answers is correct.