The correct answer is option 3, Sardar Bhagat Singh. Naujawan Bharat Sabha was founded by Bhagat Singh in 1926, when he was just 19 years old. It was a revolutionary organization that aimed to bring together the youth of India in the fight against British colonial rule. Bhagat Singh, along with other young revolutionaries, believed in the use of violence as a means to achieve independence for India. Naujawan Bharat Sabha played a key role in organizing protests, strikes, and acts of resistance against the British government. They also focused on spreading awareness about the plight of the common people and fighting against social injustices. Through their activities, Naujawan Bharat Sabha became an important force in the Indian independence movement.