Refer to the exhibit.How many broadcast domains exist in the exhibited topology?()<br /> <img src="https://nimg.ppkao.com/2018-07/xiashuhui/2018072314142046769.jpg?sign=360d114d7f7b9cb348eaa2eaffcacfbf&t=62d401f9" />
A、one
B、two
C、three
D、four
E、five
F、six