Question

energy
reacts to
products
reaction progress
more substrate was added to reaction b.
additional reactants were added to reaction b.
additional water was added to reaction b.
an enzyme was added to reaction b.

Explanation:

The dashed line (Reaction B) has a lower activation energy than the solid - line reaction. Enzymes are biological catalysts that lower the activation energy of a reaction. Adding more substrate, additional reactants, or water does not typically lower the activation energy in the way shown.

Answer:

An enzyme was added to Reaction B.