Which of the following will increase the value of a real (call) option?

Group of answer choices:

A) A decrease in the cost of obtaining the real option

B) Lengthening the time in which a real option must be exercised.

C) A decrease in the volatility of the underlying source of risk.

D) A decrease in the risk-free rate

E) An increase in the probability that a competitor will enter the market of the project in question.