Which of the Following Results Allowed Sarah Pryke, Staffan Andersson

Which of the following results allowed Sarah Pryke, Staffan Andersson and Michael Lawes (2001) to conclude that sexual dimorphism in red-collared widowbirds is the result of sexual selection by females?

A) A modification in male tail length changed female preference
B) Male tail coloration was related to their diet.
C) Males change color over their lifetime.
D) The reddest males were dominant to dull-colored males.
E) Most females mated with males with the longest-tails.