Which of the following songs was so dear to Gandhiji's heart, that he wrote: 'That one song is enough to sustain me, even if I were to forget the 'Bhagwad Gita'.
(a) Hare Ram
(b) Raghupati Raghav Raja Ram
(c) Vaishnava Jana To Tene Kahiye
(d) Ishwar Allah Tero Nam