Answer:
b. Firms become optimistic about the future and, as a result, they plan to increase their purchases of new equipment and construction of new factories
Step-by-step explanation:
Base on scenario been described in the question, the option that best explains the event that will the shift the demand curve from D1 to D2 is option b. This is so because company become hopeful that the and because of that , they plan on increasing the purchased of me equipment and building new branches as seen in the question. So option best explains the question which is the correct answer.