Top coat and nail polish are coatings which?

Top coat and nail polish are both coatings that are applied to nails. The other options are not correct as they do not accurately describe what happens when top coat and nail polish are applied. A, Melt upon application, is incorrect because these coatings are not meant to melt. B, Harden upon evaporation, is the correct answer because both top coat and nail polish will harden as the solvents evaporate and leave a film on the nails. C, Stay liquid, is incorrect because these coatings are meant to dry and become solid once applied. D, Become sticky, is incorrect because although nail polish may feel sticky before drying, it does not become sticky once applied.