Your Professor Wants You to Construct a Phylogenetic Tree of Orchids

Your professor wants you to construct a phylogenetic tree of orchids. She gives you tissue from seven orchid species and one lily. What is the most likely reason she gave you the lily?

A) to serve as an outgroup
B) to see if the lily is a cryptic orchid species
C) to see if the lily and the orchids show all the same shared derived characters (synapomorphies)
D) to demonstrate likely homoplasies