Answer:
Explanation:
radius of the solenoid, r = 0.05 m
length of the solenoid, l = 0.39 m
Magnetic field of the solenoid, B = 2 x 10^-5 T
Number of turns, N = 200
The magnetic field of the solenoid is given by

where, i be the current and n be the number of turns per unit length
n = N / l = 200 / 0.39 = 512.8

i = 0.031 A
A would be the correct answer. Its the only one to make sense since you are trying to solve the conflict!