Room temp at the end of 24 hours will be

Question

A 100 W electric bulb was switched on in a 2.5 ´ 3 ´ 3m size thermally insulated room having temperature of 20⁰C. Room temp at the end of 24 hours will be                                                                                       

      (a) 321⁰C                                                            (b) 341⁰C

      (c) 45-⁰C                                                             (d) 470⁰C