If you move farther away from Earth, does it have the same amount of gravitational force acting on you or does it change?

The strength of the force is inversely proportional to the distance squared. The farther away an object is, the weaker the force; the closer, the stronger.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

i believe your answer would be c.. : )