Length=50 cm,diameter=0.5 mm
Length=100 cm,diameter=1 mm
Length=300 cm,diameter=3 mm
Length=200 cm,diameter=2 mm
Using Hooke's law:
Y = FL/AΔL
where A = πD²/4
⇒ ΔL = KL/D²
where K = constant
For wire A: L/D² = 50/(0.05)² = 20000
For wire B: L/D² = 100/(0.1)² = 10000
For wire C: L/D² = 200/(0.2)² = 5000
For wire D: L/D² = 300/(0.3)² = 3333.33
Thus wire A has the largest extension.