A)<u>Cleaning under the fingernails when washing hands</u>
Explanation:
because that gets rid of any bacteria that is around your fingers so you don't get sick.
washing hands with only water and no soap would still leave you with bacteria
using a grater to chop vegetables isn't a good idea you could cut yourself or spread mold from cheese that may have been grated earlier if the person hasn't washed it
and using the same cutting board with meat to cut other foods isn't a good idea either because raw meat produces bacteria that can make one sick.
