Answer:
There is no change in the color of the bill's ink.
Step-by-step explanation:
There are several methods to check if the currency is counterfeit apart from all the lab related approaches, one can do a preliminary check to see if the currency is counterfeit or not.
One such method is to check if there is any color change in the bill's ink, in case there is a color change then the currency is not counterfeit. A counterfeit currency will have not color change of the bill's ink.