The correct answer is option 3: Royal Bhutan Army against the insurgents of North East India. Operation All Clear was a military operation conducted by the Royal Bhutan Army in December 2003. This operation was primarily aimed at flushing out the Indian insurgent groups that were operating in the southern parts of Bhutan. These insurgent groups were using Bhutanese territory as a safe haven and launching pad for their attacks in the Indian states of Assam, Manipur, and Nagaland.

Option 1: This option suggests that Operation All Clear was launched by the Indian Army against the NSCN (IM) in Nagaland. However, this is incorrect as the operation was actually conducted by the Royal Bhutan Army.

Option 2: This option suggests that the Indian Army and the Myanmarese Militaries conducted Operation All Clear against the insurgents of North East India. However, this is also incorrect as the operation was solely conducted by the Royal Bhutan Army.

Option 4: This option suggests that Operation All Clear was launched by the Indian Army against the militants of Jammu and Kashmir. However, this is incorrect as the operation was conducted in Bhutan and targeted Indian insurgents in the North East region.

In conclusion, option 3 is the correct answer as it