Consider the following grammar. S YaSb X +aXY XY YX| 6 | Answer the following questions based on the grammar above. 1. Which of the following variables are nullable? X Y S 2. After removing the nullable/epsilon productions, which of the following grammars can be derived? S+YaSbaSb X+aXY|6X|Y|ax|ay|a|b Y + X|b S+YaSblaSb X + aXY|6X|Y|ax|ay|6 Y + X16 S+YaSbaSb XaXY|5X|Y|ax|alb Y + Xb None of the above 3. After removing the epsilon productions and then the unit productions, which one of the following grammars can be derived? S+YaSbaSb XaXY|0X|ax|ay|a Y +aXY|bx|aX|ay|a|b o S+YaSbaSb XaXY|5X|ay|alb YaXY|bX|ay|a|b S+YaSbaSb XaXY|0X|ax|a16 Y +aXY|bx|ax|a|6 -> S+YaSbaSb XaXY|5X|ax|ay|a|b Y +aXY|6X]aX|ay|a|b 4. Which of the following productions are already in CNF? (The capital and small letters are non-terminals and terminals respectively) S XYZ S XY X Oxba