A wire of resistance 5 Ω is bent into a circular loop
and the resistance between its diametrically opposite
points is measured to be R. Now, it is stretched so that
its length is increased by twice its original. Again, it
is bent into a bigger circular loop and the resistance
between its diametrically opposite points is measured
to be R'. Then R : R' will be
A 1 : 4
B 9 : 1
C 1 : 9
D 1 : 1