B is the first sentence which sets the premise to draw the comparison between storytelling potential of Indians and others.
Sentence D follows and gives examples of two works which are evidence of exemplary storytelling by the Indians.
'They' in sentence A refers to these two epics, and the sentence claims that these two epics stand undefeated even when compared to Shakespeare and Homer.
Sentence C follows and describes another exemplary work 'Bhagavad Gita'.
So, the correct order is BDAC.
Hence, option (b) is the answer.