Lord Cornwallis is the correct answer.

Explanation:
During the late 18th century, Bengal was under British colonial rule and was a significant source of revenue for the British East India Company. The company imposed heavy taxes and extracted a large amount of revenue from Bengal, leading to significant economic and social consequences for the region.

One of the key figures associated with the extraction of revenue from Bengal is Lord Cornwallis. He was appointed as the Governor-General of British India in 1786 and introduced several policies that aimed to reform the revenue administration in Bengal.

Under Cornwallis' administration, the Permanent Settlement Act of 1793 was introduced in Bengal. This act aimed to fix the land revenue to be paid by the zamindars (landlords) and make it permanent for a period of ten years. This system of fixed revenue was expected to provide stability and ensure a regular flow of revenue for the British East India Company.

However, the implementation of the Permanent Settlement Act had several detrimental effects on Bengal. The fixed revenue imposed on the zamindars was often set at a high level, leading to excessive exploitation of the peasants and increased pressure on agricultural production. Many peasants were unable to pay the high rents and were forced into debt and poverty.

As a result of the heavy taxation and economic exploitation, a large number of peasants were unable to sustain their livelihoods and migrated to other regions in search of better opportunities. This led to a significant decrease in agricultural productivity and the transformation of large areas of Bengal into jungles inhabited only by wild beasts.

The complaints about one-third of Bengal being transformed into a jungle inhabited only by wild beasts can be attributed to the policies implemented by Lord Cornwallis. These policies, although intended to generate revenue for the British East India Company, had detrimental effects on the economic and social fabric of Bengal.