Answer
Choice B.
Work Step by Step
Treat the MRI coil as an ideal solenoid.
$$L=\frac{N \Phi_B}{i}=\frac{N \mu_0 inA}{i}=\frac{ N^2 \mu_0 A }{l}$$
Solve for the number of turns.
$$N=\sqrt{\frac{Ll}{\mu_0A}}=\sqrt{\frac{(4.4H)(2.0m)}{\mu_0\pi(0.5m)^2}}=3000$$
