4. (4 marks) Use left-factoring and/or eliminate left-recursion to transform each of the below eight grammars into a form that is suitable for recursive-descent parsing. As usual capital letters denote variables and lower case letters are terminals. (a) S + dbSc | dbaSa | cbda | baa (b) S + Sbc | Sab | ac | Sdc | (c) S Sa ba | Scc | (d) S + ccdbSa | dcaSb | ccbSa | E (e) S bbcSa | cSa | bbcad | dca (f) S + SA | E A Ab | a (g) S + abcSd | cdadS | cdabs | abb | (h) S + Sub | Sac | 6 | 0 Hint for (h): Here after elimination of left recursion you need to use also left-factoring (or vice versa)