Which of the following statements is true of using marketing to shape perceptions and expectations?

a. Preannouncements reduce excitement about a product before its release.

b. A firm that aggressively promotes its products loses its actual installed base and its perceived installed base.

c. A firm should avoid using vaporware if other vendors beat the firm to market and the firm fears that customers may select a dominant design.

d. A firm can signal its commitment to an industry by making substantial investments that would be difficult to reverse.