I don't see any error on your code, everything is well written and simple. Except trying putting PUBLIC on your Class displayer. If you encounter the same problem again try to rebuild your whole code and try to recompile the whole code. Even try restarting your personal computer.
Answer:
Five provisions of cyber ethics are:
Your computer or system should not be used to harm others. Your cyber knowledge should not be used to steal other people's resources. One should not use or copy softwares for which you have not paid. ... Never use other people's resources without their consent.
Answer:
semantic information that tells a browser how to display a page and mark up the content within a document
The answer seems to be polymerization.