13. Which of the folloiwng statements is correct? (a) If L is regular and Lin L, is regular, then L, is regular. (b) The union of infinitely many regular languages is regular. (c) If L L2 is a finite language, then L and L2 are both finite. (d) If L and L, are regular languages, then their difference (L1-L) is also regular. 14. For any alphabet , the language 0*09" is equal to ...? (a) = 0 (b) = 1 (c) = {1} (d) = 9+