A 5-year-old boy presents with temporary muscle weakness and cramping after exercise. Vital signs show HR 98/min, BP 105/68 mmHg, RR 20/min, and normal temperature. Serum creatine kinase is mildly elevated at 250 U/L post-exercise. He demonstrates normal cognitive development and no intellectual disability. He denies myalgia at rest and has normal strength between episodes. He takes no medications. Which of the following metabolic processes is most likely deficient in this patient?

1. A)Electron transport
2. B)Glycogen metabolismGABARITO
3. C)Glucogenesis
4. D)Glucose metabolism
5. E)Lactate metabolism