A group of Congress leaders who were in control of the party's organisation. It was led by K. Kamraj, former chief minister of Tamil Nadu and then the congress president. This group was known as the:

Syndicate

The correct answer is Option 3 - Syndicate

Syndicate was the informal name given to a group of Congress leaders who were in control of the party’s organisation. It was led by K. Kamraj, former Chief Minister of Tamil Nadu and then the president of the Congress party. It included powerful State leaders like S. K. Patil of Bombay city (later named as Mumbai), S. Nijalingappa of Mysore (later Karnataka), N. Sanjeeva Reddy of Andhra Pradesh and Atulya Ghosh of West Bengal. Both Lal Bahadur Shastri and later Indira Gandhi owed their position to the support received from the Syndicate.