The answer is C as shown on brainly. Theres a question posted on brainly just the exact same as yours. I'd stick with C because the person had given a full explanation to it, I can't copy & paste but I would if I could.
Hi! The contralto is the lowest among the femal voice along with the most unique among females because it’s considered the main voice that males generally have. Thus making it uncommon/unique for females to have this voice. I hope this helped, Goodluck :)
