Why do the cells in all living things need energy?

Idon’t know how to solve this question

Choose an equation that represents an enzyme-catalyzed reaction. (a) enzyme + substrate → enzyme-substrate complex (b) enzyme + substrate ←−→ enzyme + products (c) enzyme + substrate ←−→ enzyme-substrate complex → enzyme + products (d) enzyme + substrate ←−→ enzyme-substrate complex → enzyme-substrate complex + products

Which sample at stp has the same number of atoms as 18 liters of ne at stp