A mutation occurred within the DNA sequence coding for an enzyme, causing a decrease in the rate of a reaction catalysed by this mutated enzyme. Which statements could explain the decrease in the rate of reaction?

1
An inhibitor for this enzyme has an increased affinity for the enzyme and forms an enzyme–inhibitor complex more easily.
2
The active site of the enzyme might have changed shape and so is less complementary.
3
The activation energy for the reaction with the mutated enzyme is greater than with the non-mutated enzyme.