What are two best practices when it comes to Lightning Web Component events?

What are two best practices when it comes to Lightning Web Component events?
A . Use event.target to communicate data to elements that aren’t in the same shadow tree.
B . Use events configured with bubbles: false and composed:false.
C . Use CustomEvent to pass data from a child to a parent component.
D . Use event.detail to communicate data to elements in the same shadow tree

Answer: A,C