Question: Black-and-white warblers migrate from their breeding range in Canada to southern Florida for the winter. Which is most likely to occur if environmental factors limit the number of female warblers that return to Canada?

  Options: 
 A. Fewer young warblers will hatch in the spring.
 B. Warbler breeding season will start earlier.
 C. Warblers will have a larger selection of mates.
 D. Genetic diversity will increase among warblers. 
Answer: A