What type of entity instances may inherit common attributes from their entity supertype?

In database design, a subtype is a specific category that inherits attributes from a more general category known as a supertype. This relationship allows subtypes to share common characteristics defined in the supertype while still allowing for unique attributes that differentiate them.

For instance, if you have a supertype called "Vehicle," subtypes could include "Car," "Truck," and "Motorcycle." Each of these subtypes would inherit attributes such as "make," "model," and "year" from the supertype "Vehicle." Additionally, they may have their own specific attributes, like "number of doors" for cars or "bed length" for trucks. This inheritance is a fundamental concept in object-oriented design as well, enhancing consistency and reducing redundancy in data management.

The other types mentioned do not generally represent the concept of inheritance in the same way. A supertype cannot itself inherit attributes, while abstract types and aggregate types serve different purposes, focusing on structure and compiling rather than direct attribute inheritance. Thus, subtypes are the correct answer as they specifically capture the notion of inheriting attributes from a supertype.