The play "Neel Darpan" by Dinabandhu Mitra was a significant work in Bengali literature that portrayed the plight of indigo planters and their exploitation. It was later translated into English to reach a wider audience.

Option 1: Reverend James Long was not the translator of "Neel Darpan". He was an English missionary who played a crucial role in spreading awareness about the indigo planters` oppression and championing their cause.

Option 2: Dwarkanath Tagore, grandfather of Rabindranath Tagore, was a prominent social reformer and industrialist. However, there`s no evidence to suggest that he translated "Neel Darpan" into English.

Option 3: Michael Madhusudan Dutta, a celebrated poet and playwright of Bengali literature, was indeed the person who translated "Neel Darpan" into English. His translation helped bring the play`s powerful message to the English-speaking audience.

Option 4: Rabindranath Tagore, although a renowned writer and poet, was not responsible for the English translation of "Neel Darpan". He gained fame for his own literary works but did not have a direct involvement in this particular translation.

Therefore, the correct answer is option