Option 1: The statement is correct as it states that the Home Rule Movement gradually declined in 1918 after making significant progress in 1917. This decline in momentum is a factual observation.

Option 2: The statement is correct as it mentions that Annie Besant, the leader of the Home Rule Movement, did not oppose the entry of extremists. This indicates that Besant was more inclusive in her approach and allowed extremists to be a part of the movement.

Option 3: The statement is correct as it states that the Home Rule Movement became weaker due to continuous differences of opinion among nationalist leaders. This highlights the internal conflicts and divisions within the movement, leading to its weakening.

Option 4: The statement is incorrect. Mahatma Gandhi did not revive the Home Rule Movement. He was involved in various other movements like the Non-Cooperation Movement and the Civil Disobedience Movement, but not the revival of the Home Rule Movement.

In conclusion, the correct answer is option 4, as Mahatma Gandhi did not revive the Home Rule Movement.