Which of these was a cavalry regiment of British Army from 1678 until 1971 when they amalgamated with 3rd Carabiniers?

Question

Which of these was a cavalry regiment of the British Army from 1678 until 1971, when they amalgamated with the 3rd Carabiniers (Prince of Wales's Dragoon Guards)?

ARoyal English Blacks

BRoyal Scots Greys

CRoyal Welsh Blues

DRoyal Irish Reds

Select from the options above.

Correct Option: 2