GATE Electronics and Communications (EC) 2016 Shift 2 Solved Paper

Consider a long-channel NMOS transistor with source and body connected together. Assume that the electron mobility is independent of 𝑉_𝐺𝑆 and 𝑉_𝐷𝑆. Given, g_m = 0.5 𝜇A/V for 𝑉_𝐷𝑆 = 50 mV and 𝑉_𝐺𝑆 = 2 V,
g_d = 8 𝜇A/V for 𝑉_𝐺𝑆 = 2 V and 𝑉_𝐷𝑆 = 0 V,
Where ${\mathit{g}}_{\mathit{m}}=\frac{\partial {\mathit{I}}_{\mathit{D}}}{\partial {\mathit{V}}_{\mathit{G}\mathit{S}}}$  and ${\mathit{g}}_{\mathit{d}}=\frac{\partial {\mathit{I}}_{\mathit{D}}}{\partial {\mathit{V}}_{\mathit{D}\mathit{S}}}$ 
The threshold voltage (in volts) of the transistor is ________.