Among the following, the quantity that is termed as gyro magnetic ratio is 
(m_e - mass of electron, e - charge of electron)

$\text{ As we know the formula gyromagnetic ratio }=\frac{L}{M}$

$\text{ angular momentum }\left(\mathrm{L}\right)=\frac{\mathrm{nh}}{2\pi }$

$\text{ Magnetic moment }\left(M\right)=n\times \text{ Bohr magneton }=n\times \frac{eh}{4\pi \mathrm{m}}$

$\text{ So, gyromagnetic ratio }=\frac{\frac{\mathrm{nh}}{2\pi }}{\mathrm{n}\times \frac{\mathrm{eh}}{4\pi \mathrm{m}}}=\frac{\mathrm{e}}{2\mathrm{m}}$