The correct answer is option 4, Lord Ripon.

To understand why Lord Ripon is associated with the introduction of the principle of local self-government in India, we need to look at his tenure as Viceroy of India from 1880 to 1884.

During his time as Viceroy, Lord Ripon implemented significant reforms aimed at decentralizing power and giving more autonomy to the local government bodies. One of his key achievements was the passing of the Local Self-Government Act of 1882, also known as the Ripon Act.

This act marked a significant step towards empowering Indians at the grassroots level. It introduced elected representatives in local bodies such as municipal corporations, district boards, and local boards, thereby allowing Indians to participate in the governing process. The concept of self-government at the local level was a significant departure from the previous centralized system of governance.

Lord Ripon`s efforts in introducing the principle of local self-government laid the foundation for further democratic developments in India`s political history. It played a crucial role in the growth of the Indian National Movement and the eventual attainment of independence.