A 6-year-old boy was admitted to the hospital for treatment of acute post-streptococcal glomerulonephritis, on the second day of the admission he developed a headache, nausea, and vomiting with a disturbed level of consciousness. The MOST likely cause of these new symptoms is:
a. Acute renal failure
b. Electrolytes disturbance
c. Hypertensive encephalopathy
d. Meningitis Volume overload