Consider the following groups:

 

 

 

 

(a)  How many groups can show –M effect when attached to a conjugated system?
 (b)How many groups can show +M effect when attached to a conjugated system?
 (c)How many groups can show +I effect?
 (d)How many groups can show –I effect?
If answer of part (a) is 1, part (b) is 2, part (c) is 3 and part (d) is 4 . Write 1234 in answer sheet.