Excerpt from Book of Etiquette Lillian Eichler

Various foods are eaten with the fingers instead of fork or spoon. Bread, for instance, is never cut but always broken into small pieces and lifted to the mouth with the fingers. Butter is seldom provided at the formal dinner, but if it is, each little piece of bread is buttered individually just before it is eaten. Crackers and cake are eaten in the same way; although some cakes and pastries are eaten with the fork. Those that can be eaten daintily with the fingers such as macaroons, lady-fingers, cookies, etc., should be eaten so while layer cake and elaborate pastries should be eaten with the fork.
What is the author's purpose in writing this passage?

A) to inform
B) to persuade
C) to frighten
D) to entertain