It is believed that keeping poultry in brightly lit cages significantly increases the amount of head-pecking among them. However, in recent experiments, commercially reared chickens when kept in brightly lit cages were found to behave much less aggressively; instead, they indulged in an almost “sleepy” behavior – they tended to mostly put their heads between their wings and seemed to doze off, an action unusual for such chickens. This raises serious questions on the belief that the visibility accorded by the bright lights is majorly responsible for the increased display of head pecking among the poultry.
Which of the following, if true, most seriously weakens the argument?
A. The pecking order is established early in a chicken's life when raised in a flock; the young chicks peck each other and bully one another when they are around food.
B. Head-pecking, is almost always the result of high stress levels and when that happens, the birds will sometimes pluck each other’s feathers out, and can really hurt one another.
C. Commercially reared chicken when put in cages are often equipped with blinding glasses that prevent more than 90% of the light from entering the retina.
D. While Commercially reared chicken in the experiment exhibited a docile behaviour in cages, they were much more aggressive a few hours later when allowed to roam freely on the farm.
E. While most chicken in the experiment exhibited a docile behaviour when in cages, a few were unusually aggressive.