An increasing number of Chinese have been making use of the roofs of modern buildings, like this "sky farm" built on the rooftop of a 4-storey shopping mall in Hefei, Anhui province. The farm, covering an area of 7,800 square meters, has 23 types of vegetables grown in it, as well as various kinds of poultry. It includes a zone to raise chickens for adoption as well as peacocks.
How many types of vegetables has been grown in the "sky farm"?
A. 23
B. 24
C. 25