4. Circle one of the letters R, C or N for each language given below. Circle R if the language is regular (and of course also context-free), circle C if the language is context free but not regular, and circle N if the language is not context free. Note that xR denotes the string x written backward. 1. aibick | i,j,k 2 0 and k 2 9) circle one: R CN 2. a bick I i,j,k 2 0 and k 2 j) Circle one: R C N 3. a bick i,j,k 20 and k 2 j2 iCircle one: R C N 4. a10i b3k I i, k20 and k >99) Circle one: RC N 5. a5i b99k c551 i,k 2 0) Circle one: R C N 6. a5i b2i c3k I i, k2 0 and i > k) Circle one: RCN 7. { aibk ci | i, k 0, and i