Continents are made of.

A.) played
B.) lithosphere
C.) crystal rock
D.) mantle rock

A continent is a large land mass and its surrounding shallow continental shelf. Both are composed primarily of granite, which is lighter than the liquid mantle of the Earth and therefore floats upon it like cork on water.

Granite would be the correct answer but i see you don't have that there, Lithosphere i would say may be the right answer. or this

The continents are made out of relatively brittle rock called the "Crust"

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.

examples of nucleic acids are deoxyribonucleic acid (dna) and ribonucleic acid (rna).