The degree of freedom of mixture of two ideal gases having moles `n_1` and `n_2` and degree of freedom `f_1` and `f_2` respectively, is

Options

A. `[f_(mix) = (n_1f_1 + n_2f_2) / (1/n_1 + 1/n_2)]`
B. `[f_(mix) = (n_1f_2 + n_2f_1) / (n_1 + n_2)]`
C. `[f_(mix) = (n_1f_1 + n_2f_2) / (n_1 + n_2)]`
D. `[f_(mix) = (n_1/f_1) +( n_2/f_2) / (n_1 + n_2)]`