Which one of the following sets of exchange rates shows "cross-rate equality" (or"consistent cross rates")?

Question

Quizplus · Accepted Answer

To check for cross-rate equality, we need to make sure that the cross rates between different currencies match up. 
In option C, we see that 2 Swiss Francs = $1 and 1 Swiss Franc = € ⅓, which means that 1 € = 6 Swiss Francs. And from the last rate, we have €1 = $1.50, which implies $1 = €2/3. 
Now, we can calculate the cross rate between Swiss Francs and Dollars as follows:
2 Swiss Francs = $1
1 Swiss Franc = €⅓ = $2/3
Therefore, 2 Swiss Francs = $1 = 3 * $2/3 = €2 
This matches the actual exchange rate given in the last line, which confirms that the cross-rates are consistent.

Which One of the Following Sets of Exchange Rates Shows