Explanation

The Assam Rifles, raised in 1835 as the Cachar Levy to guard British settlements against tribal raids, is the oldest central paramilitary force in India. The Central Reserve Police Force (option A) was raised much later in 1939 as the Crown Representative's Police. The Border Security Force (option B) was created in 1965 in the wake of the Indo-Pak war. The Commando Battalion for Resolute Action or CoBRA (option D) is a specialised anti-Naxal unit of the CRPF raised in 2008–09. Hence option C.