If you were the manager of a clothing store and wished to notify your employees of a change in the store’s hours, you would probably write

a. a business letter
b. a personal letter
c. an instant message
d. a memorandum

B). Personal letter.

Explanation:

A personal letter would best accomplish the manager's purpose to notify his employees regarding the shift in store's hours as a common personal message to all the employees would help inform them about the change individually and therefore, more clearly. However, a personal letter includes personal matters and is not considered for professional matters yet in the given case, it would best serve his purpose. Thus, option B is the answer.