Glycolysis and gluconeogenesis share multiple enzymes. This is possible because the reactions catalyzed by the shared enzymes

a. do not generate ATP or reduced electron carriers.
b. have free energy changes near zero.
c. require fewer substrates.
d. have smaller activation energies.

Option B. "have free energy changes near zero"

Explanation:

Glycolysis is the process in which glucose is converted into pyruvate with the help of multiple enzymes. The pyruvate is then processed to synthesis ATP and further consumed in other pathways.  

Multiple enzymes such as  hexokinase, phosphofructokinase, and pyruvate kinase are used in this process. The ATP produced in this process contain phosphate group which has very high high free energy of hydrolysis which further results in a large decrease in free energy.

Gluconeogenesis is the process in which glucose is recovered from different subsrate with the help of multiple enzymes including pyruvate carboxylase, Phosphoenolpyruvate (PEP) carboxykinase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase. PEP, has a very large free energy of hydrolysis whic is prepared by transfer of phosphate from ATP to reverse the glycolysis process.

Hence, the correct option is B.