The compound ratio of 5:6, 3:2 and 4:5 is?  Choose the correct option:
A) 3 : 5
B) 2 : 7
C) 1 : 1
D) 1 : 4
E) none

Rationale: "answer : option c 5 / 6 : 3 / 2 : 4 / 5 = 1 : 1"
Answer: C