As we know Bohr model is only applicable for H-atom and hydrogen like atom (e.g. He⁺, Li⁺⁺ etc). So option (a) & (b) are correct on the other hand Bohr model for the spectra of H-atom need not necessary to valid only at room temperature and never predicts continuous as well as discrete spectral lines. So options (c) & (d) are wrong.

Therefore option (a) & (b) are correct.