Answer: Send a memo
Explanation:
Memo is stand for Memorandum and it is usually use for written some useful information for the business purpose.
Memo is known for its high versatile communication and it is usually used for the business purpose.
The memo is written for informing the readers about some new information, policies and about prices change in the business organization. The memo is basically divided into the two main parts that are:
Therefore, Ann should use a memo for informing about the hiring policies among more than hundred employees.