A: assist his breathing with a bag-mask device, establish vascular access, and administer 5 mg of diazepam.
B: apply high-flow oxygen via nonrebreathing mask, place him on his side, and wait for the seizure to stop.
C: intubate him to prevent aspiration, establish IV or IO access, and administer 0.1 mg/kg of lorazepam.
D: administer 0.5 mg/kg of diazepam rectally, cover him with a blanket, and administer high-flow oxygen.