Is there any risk involved in taking out a mortgage, which could cause the Economic Net Benefit(Mortgage) to be less than predicted or even negative? Why?

A  No, there is no risk because the expected return in the stock market is guaranteed.

B  There is risk in taking out a mortgage. The 10% expected return in the stock market is not guaranteed, and the return could end up being less than the mortgage interest rate. This would cause the spread to become negative, which would cause the Economic Net Benefit(Mortgage)   to become negative.

C  There is risk because the mortgage interest rate could unexpectedly increase.  This would cause the spread to become negative, which would cause the Economic Net Benefit(Mortgage)   to become negative.

D  None of the available answers