Which of the following is/are example(s) of different types of real options?

a) You will defer the start of a project to gain more additional information regarding the value of the investment.

b) You want to shut down three projects or sell them to other companies to reduce the scale of your investment.

c) You will enhance the flexibility into the firms production facilities so that the firm can use cheapest raw materials or produce the most valuable set of outputs.

d) All of the above.