Step 1: Plan
The options differ in only two things: whether (A) is included, and which of (C) and (D) are included. We will test (A) first, because it decides between several options.
Step 2: Test statement (A)
The famous leader of the Syndicate was K. Kamaraj of Tamil Nadu. He was the Congress president in 1964-67 and the main kingmaker. Nijalingappa was part of the group, but the group was not led by him. So (A) is wrong.
Step 3: Use this to cut options
Options 1, 2 and 4 each include (A). Since (A) is wrong, all three are out. Only option 3 does not include (A).
Step 4: Confirm statement (B)
The name Syndicate was used for the group of senior leaders who held the party organisation in their hands. This is accurate, and it is part of option 3.
Step 5: Confirm statement (C)
In 1969 the party split over the presidential election and other issues. The old guard formed the Congress (O). The Syndicate leaders went with it. This is accurate, and it is part of option 3.
Step 6: Confirm statement (D)
Patil, Sanjeeva Reddy and Atulya Ghosh were all strong regional leaders in the Syndicate. They came from different States, which is why the group had so much weight in the party. This is accurate, and it is part of option 3.
Final Answer:
Only B, C and D hold true, so option 3 is the answer.
\[ \boxed{\text{Option 3}} \]