The orbital magnetic dipole moment of electron in hydrogen atom is

Question

$(a)\;\mu=\large\frac{e h n}{\pi m}\qquad(b)\;\mu=\large\frac{e h n}{2 \pi m}\qquad(c)\;\mu=\large\frac{e h n}{4 \pi m}\qquad(d)\;\mu=\large\frac{ 2e h n}{\pi m}$