3. Closure Properties of context free languages. (a) Closure under reversal operator. Show LR = {WR| W E L} is CFL if L is context-free. (b) Closure under prefix operator. Prefix operator is defined as: prefix(w e S*) = {wi -- Wk| OS k = [w]}. For example, if a string w = asu, prefix(w) = {,a, as, asu}. Show Prefix(L) = {prefix(w)| W E L} is a CFL if L is context-free. (c) C = {abc" | n>0} is not context free. Use the context free languages A = {a"b"c"| m, n >0} and B = {ab cm|m, n >0} along with C to show that the class of context-free languages is not closed under intersection. (d) Use part (c) and De Morgan's law (AUB= NB) to show that the class of context-free languages is not closed under complementation