They used faster or slower speeds in the model, and calculated how long it
would take particles to leave the
surfaces.
How does this detail develop the article's central
idea?
А
It shows how scientists found out how long to
wash your hands.
B
It shows why scientists wanted to study how
long to wash your hands.
C
It shows how long it took scientists to find out
how to best wash your hands.
D
It explains a past study used to find out how
to best wash your hands.