Which Hyper Text Markup Language 5 (HTML5) option presents a security challenge for network data leakage prevention and/or monitoring?

Which Hyper Text Markup Language 5 (HTML5) option presents a security challenge for network
data leakage prevention and/or monitoring?

A.
Cross Origin Resource Sharing (CORS)

B.
WebSockets

C.
Document Object Model (DOM) trees

D.
Web Interface Definition Language (IDL)