An experiment compared the adhesion of 2 types of paint A and B to 3 types of metal, 1, 2 and 3, used in automobiles. Thirty sheets of metal were used in the experiment 10 of Metal 1, 10 of
Metal 2 and 10 of Metal 3. Half of each metal type will receive paint A and the other half will receive paint B. The adhesion of the paints was measured, and the measures were compared. How
many experimental units are in the experiment?
A- 2
B- 3
C- 10
D- 30
E- 60
