In a certain flower shop, which stocks fou
题型：单项选择题
问题：
In a certain flower shop, which stocks four types of flowers, there are 
as many violets as carnations, and as many tulips as violets. If there are equal numbers of roses and tulips, what percent of the flowers in the shop are carnations ？（）
A.10%
B.33%
C.40%
D.50%
E.60%