A user can enter a null value into a primary key field.

Are the rules mutually exclustive?

Consider a binary classification problem with the following set of attributes
and attribute values:
• Air Conditioner = {Working, Broken}
• Engine = {Good, Bad}
• Mileage = {High, Medium, Low}
• Rust = {Yes, No}
Suppose a rule-based classifier produces the following rule set:

If objects of all the classes derived from the same base class all need to draw themselves, the draw function would most likely be declared:

a. private b. virtual c. protected d. friend