Concept:Idul-Adha teaches complete obedience to Allah and the prohibition of human sacrifice.Explanation:Muslims remember Prophet Ibrahim's willingness to sacrifice his son in obedience to Allah.Allah replaced his son with a ram, showing that human sacrifice is not acceptable.Therefore, Muslims are cautioned to avoid human sacrifice and instead offer animal sacrifice.This is one of the important lessons of Idul-Adha.Answer:B. Are cautioned not to engage in human sacrifice