challenge: What was the outcome of a molecular phylogenetic study comparing mitochondrial DNA sequences published in 2009 regarding the genus Anas?
  
  A. The genus Anas was split into four monophyletic genera
  B. The genus Anas was split into two monophyletic genera
  C. The genus Anas was merged with the genus Spatula
  D. The genus Anas was found to be monophyletic and unchanged
  Answer: 