Atp is a compound produced by the body to:
a. break down proteins
b. attack materials foreign to the body
c. carry oxygen to the cells of the body
d. be used as a source of energy when needed for a reaction

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs

the scientific method.