A key is a real-world, generally accepted identifier used to uniquely identify real-world objects.

Answer with Explanation:

Provided that Mandy's Table is this.

[ x ][ 1 ][ 2 ][ 5 ][ 10 ]

-------------------------------

[ y ][ 5 ][ 10 ][ 25 ][ 50 ]

5/1 = 10/2 = 25/5 = 10/50

"Proportional relationship" refers to an equal set of ratios in a statement or a table which shows "equivalent ratios."

As seen in Mandy's table, the last set if ratio is not equivalent to the other set of ratios because Mandy has incorrectly written the ratio. Instead of , she wrote . So, this makes it not equivalent to .

The table is actually proportional, but Mandy made an error in writing the last ratio, that's why it looks not proportional.

So, this explains the answer.