A long active seizure

A 10-year-old boy is brought to the emergency room by his mother due to a long active seizure. He was hospitalized two months ago for status epilepticus and was prescribed valproic acid.
What is the first step of action?

A-Intravenous injection of haloperidol
B-Intravenous fluids
C-Airway stabilization and 100% oxygen
D-Gastric lavage
E-Electroencephalogram (EEG)