If you slowly increase the strength of an electric current flowing through the wire, you would expect the magnet to become stronger. The correct option among all the options that are given in the question is the first option or option "a". The magnetic field around the wire becomes stronger. I hope it helps you.
Square Perimetre = Side x 4
So a length of a square ground is 160/4 = 40 (m)
Absolute value means the distance from 0.
|-0.45| =0.45
|-0.0045|=0.0045
0.45>0.0045
So
|-0.45|>|-0.0045|
