Option 1: K.T. Telang - This option is not the correct answer. K.T. Telang was not the editor of the journal Indian Social Reformer.
Option 2: Veeresalingam - This option is not the correct answer. Veeresalingam was also not the editor of the journal Indian Social Reformer.
Option 3: N.G. Chandavarkar - This option is not the correct answer. N.G. Chandavarkar was not the editor of the journal Indian Social Reformer.
Option 4: K.N. Natarajan - This option is the correct answer. K.N. Natarajan was the editor of the journal Indian Social Reformer that was started in 1890.
The journal Indian Social Reformer was an important publication during the Indian national awakening period. K.N. Natarajan served as its editor and played a crucial role in promoting social and political reform in India. He used the platform of the journal to advocate for issues such as women`s empowerment, education reform, and the eradication of caste discrimination.
Overall, option 4 - K.N. Natarajan is the correct answer as he was the editor of the journal Indian Social Reformer.