PLS HELP Does anyone know the answer to the question on the bottom?

100mg magnesium reacts with 20ml of 1.0m hcl

  the mississippians were considered to be  horticulturalists, which means they were

The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is made to illustrate which of the following? a. that atoms are indivisible b. that atoms are very small c. that atoms are very large d. that in a copper penny, there is one atom for every person on earth