A persons height in centimeters and that same persons height in inches... When the input is in centimeters you can convert to inches which is actually a function. Also this was the only one that had any relation to each other like at all
In a function, each input has to be paired with exactly one output.
For example, in the first choice, there could be 40 people with different heights and at the same age. That would not work, because then (12, 52) and (12, 64) and a thousand other combinations could work.
If you eliminate each choice like this, the only thing left is the third choice.
