Which one of the following is an example of a "flexibility" option? a. A company has an option to close down an operation if it turns out to be unprofitable. b. A company agrees to pay more to build a plant in order to be able to change the plant's inputs and/or outputs at a later date if conditions change. c. A company invests in a project today to gain knowledge that may enable it to expand into different markets at a later date. d. A company invests in a jet aircraft so that its CEO, who must travel frequently, can arrive for distant meetings feeling less tired than if he had to fly commercial. e. A company has an option to invest in a project today or to wait a year.