Final answer:
Discretionary access control is considered to be the least restrictive access control model. Users have the freedom to make decisions about granting or revoking access rights, providing flexibility and customization.
Step-by-step explanation:
Discretionary access control is considered to be the least restrictive access control model. It is based on the owner or administrator of a resource granting or denying access to other users or entities.
Under discretionary access control, users have the freedom to make decisions about granting or revoking access rights, hence the term 'discretionary'. This model allows for flexibility and customization, but it also requires a high level of trust in the resource owner's decision-making.
In contrast, other access control models such as mandatory access control and rule-based access control enforce more rigid access policies that are determined by system administrators or predefined rules.