Create UML class diagrams based on the following design patterns:

Factory Method

Singleton Pattern

Observer Pattern

Decorator pattern

Model-view pattern

A company named "Acme Inc." is facing a decline in sales and customer satisfaction. The management team has noticed that the company's products are not meeting the changing needs and preferences of their target market, and the company's marketing efforts are not effectively reaching potential customers. The management team has asked you, as a consultant, to help solve this business problem by conducting market research, analyzing consumer behavior, and recommending strategies for product development and marketing.

Thank you!