Atransmutation reaction must always involve a(n)
a. change in the number of electrons in the atom
b. decrease in the number of neutrons in the nucleus of an atom
c. increase in the number of neutrons in the nucleus of an atom
d. change in the number of protons in a nucleus of an atom

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).