Concept:Natural incubation uses a brooding hen to hatch eggs.Explanation:The main disadvantage is that the hen may sometimes abandon the eggs before hatching.This cause is unpredictable and reduces the hatchability of the eggs.Artificial incubation is usually more reliable in this regard.Thus, of the given options, abandonment by brooding hens is the correct drawback.Answer:C. the brooding hens sometimes abandon the eggs