By US law, exit signs in buildings must be one of what two colors?

More Questions:

What is the practice of creating decorative shapes by trimming trees and shrubs?

What is known as the "Mary Celeste"?

Who invented basketball?

What sport's lingo uses the term "Cesta"?

According to Thomas Malory, Sir Bedivere's last knightly act is to return what to a lake?

What river do the Holland Tunnel and Lincoln Tunnel pass beneath?

What Australian island is named for the man who circumnavigated Australia and discovered New Zealand?

What are baby bears called?

What hormone secreted by the pancreas lowers blood glucose levels in diabetics?

What is an organism called that lives on or in a host animal?

Whose 1984 album "Ride the Lightning" features an electric chair on the sleeve?

What is the avian name of the acronymic evil organization on "The Man from U.N.C.L.E."?

How old was Lady Diana when she married Prince Charles?

What famous horse belonged to Napoleon?

What is the reality TV show based on the Robertson Family?