Question ID:PT86 S1 Q18 Passage:In an island nature preserve, Common Eider nests are found in roughly equal numbers in highly concealing woody vegetation, wooden boxes, and open grasslands that do not conceal nests. Some Common Eiders lay their eggs in nests established by other Common Eiders, probably in order to locate them in an area that is maximally safe from predation. Although one would expect the nests concealed in woody vegetation to be most commonly selected by other females for laying their eggs, the female Common Eiders that lay their eggs in other birds' nests most commonly select established nests in wooden boxes.  Stem:Which one of the following, if true, would most help to explain why, in this nature preserve, Common Eiders that lay their eggs in other birds' nests most commonly select established nests in wooden boxes? Correct Answer Choice:BChoice A:Some Common Eiders that lay their eggs in nests established by other Common Eiders have been observed, in subsequent years, building nests of their own in the nature preserve. Choice B:Established nests concealed in woody vegetation are difficult for Common Eiders to detect. Choice C:Defensive behavior by nest builders can sometimes deter intruding Common Eiders. Choice D:Virtually all of the island nature preserve consists of habitats that have been, at some point in the past, altered by humans. Choice E:Foxes and other natural predators of the Common Eider are not uncommon in the island nature preserve.