Which of the following enzymes only operate in gluconeogenesis (not glycolysis)? (select all that apply)

a) Glucose 6-phosphatase
b) Fructose 1,6-bisphosphatase
c) Glyceraldehyde 3-phosphate dehydrogenase
d) Phosphoenolpyruvate carboxykinase
e) Pryuvate carboxylase
f) Phosphoglucose isomerase