单选题 According to the passage, which of the following determines the shape and coloring of the plumage of a given species of bird within a given ecological niche?

• (A) The emergence of a competing species who rely upon the same food source as the first species
• (B) The physical appearance of the food supply available in the niche to the given species
• (C) The ability of the first species to collect and make use of the nutritional properties of the food within in the niche
• (D) The physical appearance of rival males within the species who compete for both the same food supply and females
• (E) The physiological effects on fertility of the food available in the niche