Resistance R = 8 ohm
let's take length as L
and cross section area as A

here we need to use the formula R= rho(L/A)
here rho (as i didn't find the Greek symbol for it) stands for resistivity

as length is halved and r the radius is increased by two
R is reduced to R/4=8/4=2 ohm

so new resistance will beĀ  2 ohm
1 4 1