Isotopes include two or more versions of an atom of a given element that have the same number of protons but a different number of neutrons.  The isotope in this question is a charged atom, also known as an ion. They have unequal numbers of protons and electrons. An isotope symbol communicates information about the element (specifically, the symbol), the atomic number of that element, the mass number of the specific isotope of the atom, and the electrical charge on the ion.
 

Every reaction has an activation energy and an enthalpy change. Both of these values can be determined from an energy profile. The energy profile shows the energy of reactants (initial energy), the energy of products (final energy), and the energy at the peak of the graph (referred to as the activated complex). You have to use these three values in order to compare the enthalpy change and the activation energy for the two pathways. Here's how to do that:

The enthalpy change is the difference in energy between reactants and products. So use the coordinates on the vertical axis to determine (estimate) the reactant energy (initial value) and the product energy (final value). Then subtract. That's the enthalpy change. Now compare the two values for Pathway A and Pathway B and answer the first question.

The activation energy is the difference in energy between reactants and the peak location on the graph (activated complex). So use the coordinates on the vertical axis to determine (estimate) the reactant energy (initial value) and the peak energy (highest value of curve). Then subtract. That's the activation energy. Now compare the two values for Pathway A and Pathway B and answer the second question.

Now the two different graphs represent two different pathways between reactants and products. One of the pathways is catalyzed. That is a catalyst is used and serves the function of increasing the reaction rate by lowering the activation energy. The catalyzed pathway is the pathway with the lowest activation energy.  Now you can answer the third question.