Question

What is an abstract class?

(a) A class that has direct instances, but whose descendants may have direct instances

(b) A class that has direct instances, but whose descendants may not have direct instances

(c) A class that has no direct instances, but whose descendants may have direct instances

(d) All of the mentioned

The question was posed to me in an interview for internship.

My query is from Unified Modelling Language topic in division Design and Implementation of Software Engineering

Answer 1

Correct choice is (c) A class that has no direct instances, but whose descendants may have direct instances

The explanation is: An abstract type is a type in a nominative type system which cannot be instantiated directly.