What do all ecozones have in common?

Which of the following describes what rocks usually are composed of ,

Religious conflict in northern ireland started with a) cultural differences resulting from viking invasions around 800 b) england’s split from the catholic church in the 1500s c) rebellions in ireland between 1916 and 1921 d) the norman invasion of england in 1066

Which statement best describes how chemical equations demonstrate conservation of mass?