Which type of fire extinguishers can a Class D fire extinguisher license maintain?

A Class D fire extinguisher is specifically designed to combat fires involving combustible metals, such as magnesium, titanium, and sodium. These types of fires cannot be extinguished using water-based or foam extinguishers, as they may exacerbate the situation by reacting with the metals.

The correct option indicates that a license holder can maintain both dry chemical and dry powder extinguishers. Dry chemical extinguishers often include agents that can smother or break the chemical reactions occurring in Class D fires, making them effective in certain scenarios. Dry powder extinguishers are also specially formulated with agents that can effectively suppress combustible metal fires without creating hazardous reactions.

Given this context, the reason why the other options are less suitable is that water-based and foam extinguishers do not provide the necessary effectiveness or safety required for Class D fires, while the option encompassing all types of extinguishers is too broad and not specific to the requirements of maintaining a Class D extinguisher. Thus, focusing on dry chemical and dry powder extinguishers aligns with the proper training and use cases associated with handling Class D fire situations.