The following description of class selector of CSS is correct:
A.
Class selector names start with "#" followed by English symbols。
B.
Class selector names start with "." followed by an English symbol。
C.
Class selector only needs to be defined, and the style will change automatically after it is defined。
D.
When applying a class selector, you need to introduce a class selector through the ID attribute, such as < p id="class selector">。