Let R1 and R2 be regular sets defined over the alphabet, then
- A. R1 intersection R2 is not regular
- B. R1 union R2 is not regular
- C. Sigma* - R1 is regular
- D. R1* is not regular
Answer: C. Sigma* - R1 is regular
Explanation: Regular languages are closed under intersection, union, complement, and Kleene star.