Respuesta :

A. 2:1 = 1:2

Hope this helps. :/
The answer is D because if I cut a pie into 4 pieces and ate 3, it's the same amount as if I cut a pie into 12 pieces and ate 9. To realize this, 3x3 is 9 and 4x3 is 12 therefore 3:4 = 9:12