HP

simple tarika : put a,b,c,d as 1/4,1/3,1/2,1 or anything else
or
u know that 2/b=1/a+1/c
and
2/c=1/b+1/d

use the above facts to deduce the equation as 2ac+cd=ab+2bd
u know that bd>ac so ab<cd

i proved it without putting values..its not safe when an option "None of these" is there..its easy..

tell me if ne1 wants solution ??
Ans is C