What is the name given to the piece of equipment umpires use to identify the playing positions on the court

What is a principle of design that repeats elements to create good visual flow?

What does it mean to have a bias (for example your bias of bts)?

Which description most closely matches a typical country song? a - a song with simple and direct lyrics b - a song with complicated harmony and melody c - a song with instrumentation but no lyrics d - a song based on an old english ballad