Question

Which of the following is true?

(a) Every subset of a regular set is regular

(b) Every finite subset of non-regular set is regular

(c) The union of two non regular set is not regular

(d) Infinite union of finite set is regular

This question was posed to me at a job interview.

This key question is from Regular Language & Expression topic in division Regular Expressions and Languages of Automata Theory

Answer 1

Right option is (b) Every finite subset of non-regular set is regular

For explanation: None.