A. 5/6 is your answer
Proof:
(8/10)/(2/2) = 4/5
(8/10)(2/2) = 16/20
(8/10)(5/5) = 40/50
hope this helps
The values of the expressions B, C and D are all 0.8. The value of expression A is 5/6, or 0.83333... , so this is the exception to the rule (value = 0.8).