Explanation: Murshid Quli Khan, who served as the Nawab of Bengal from 1717 to 1727, was a significant figure in the history of West Bengal. His rule was marked by several important contributions, but his most notable achievement was the stabilization and security of Bengal from both external and internal threats.
Murshid Quli Khan was appointed as the Nawab of Bengal by the Mughal Emperor Farrukhsiyar in 1717. At the time, Bengal was facing numerous challenges, including internal rebellions and external threats from neighboring regions and European powers. The region was also suffering from economic instability and administrative inefficiencies.
One of the primary threats to Bengal during Murshid Quli Khan's rule was the Maratha invasions. The Marathas were a powerful military force that posed a significant threat to the stability of the region. Murshid Quli Khan took several measures to strengthen the military and administrative structures of Bengal to counter these threats. He fortified the borders, improved the military infrastructure, and established a more efficient administrative system to ensure the security of the region.
Internally, Murshid Quli Khan faced challenges from local chieftains and zamindars who often rebelled against the central authority. He took steps to consolidate his power and suppress these rebellions, thereby ensuring internal stability. His efforts in this regard were crucial in establishing a more unified and secure Bengal.
While Murshid Quli Khan did recognize the importance of trade and made some efforts to promote it, this was not his primary focus. His main contribution was in securing Bengal from both external and internal dangers, which laid the foundation for the subsequent growth and prosperity of the region.
In summary, Murshid Quli Khan's most significant contribution was his role in freeing Bengal from external and internal dangers, thereby ensuring the stability and security of the region. This achievement is why option D is the correct answer.