The graph above shows the progress of a chemical reaction. based on the graph, which of the following is true?

reaction a is enzyme-catalyzed, while reaction b is not enzyme-catalyzed.
reaction a is not enzyme-catalyzed, while reaction b is enzyme-catalyzed.
reaction a uses cofactors, while reaction b does not use cofactors.
reaction a and reaction b use cofactors.

Reaction A is not enzyme-catalyzed, while reaction B is enzyme-catalyzed

Explanation:

The minimum energy required by the reactants to cross the energy barrier is called as activation energy. The use of enzyme lowers the activation energy as it takes the reaction through a different pathway which is lower in energy. Thus a enzyme catalyzed reaction has low activation energy as compared to a non catalyzed reaction.