Answer
A>B>C
Work Step by Step
Electric field is inversely proportional to Radius of ring and disk
so electric field in A in stronger than B and C(bcz of smaller distance)
Electric Field in B become Half bcz radius is got double. its field is greater than C but less than A
Electric field in C is very week bcz of linear charge distribution there isn't any charge in between radius R
hence proved
A>B>C
