A large number of consecutive IP addresses are available starting at 198.16.0.0. Suppose that four organizations Aerie, Boston, Castle and Daron request 4000, 2000, 4000, and 8000 addresses, respectively and in that order. Which of the following is correct mask for organization Castle?
A 198.16.24.0/20
B 198.16.0.0/20
C 198.16.64.0/19
D 198.16.128.0/20