The correct answer is: D. Sridhar Mishra.
Gautam Mahakavya is an epic poem written in Magahi language by Sridhar Mishra. It is a story of Gautama Buddha, the founder of Buddhism. The poem is divided into 12 cantos and tells the story of Gautama Buddha’s life from his birth to his enlightenment.
Yamuna Pathak was a Magahi poet who wrote several poems in the Magahi language. However, she did not write Gautam Mahakavya.
Yogeshwar Singh was a Magahi writer who wrote several novels and short stories in the Magahi language. However, he did not write Gautam Mahakavya.
Harihar Pathak was a Magahi poet who wrote several poems in the Magahi language. However, he did not write Gautam Mahakavya.