During the classical era, composers stopped writing pieces that included a. major scales. b. the piano. c. continuo. d. metered rhythm

The answer should be D, Metered Rhythm.

option c (nickel) is not found in earth's crust. the earth's crust basically contains eight (8) elements namely: oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium (listed in order of abundance).