To be able to determine which among the choices is a proportion, you check if each side has the same common ratio.
A. 8/10 = 6/8
Ratio: 0.80 = 0.75 (Not Proportional)
B. 3/4 = 12/15
Ratio: 0.75 = 0.80 (Not Proportional)
C. 4/6 = 9/12
Ratio: 0.67 = 0.75 (Not Proportional)
D. 6/9 = 8/12
Ratio: 0.67 = 0.67 (Proportional)
Since the ratio of each side of letter D is equal, Letter D is the one that is in Proportion.
