New things happen every day, something historic oftens goes down. Things such as:
New inventions (Ex: The first touch-screen phone)
New records (Tallest building)
New presidents and prime ministers (US election of Donald J Trump, 2016) The results of the winter Olympic games (This February.)
Almost anything that happens is a historical record of everything else. Interpretations may change on evidence found or other discoveries, example: the theory of plant cells has changed as more and more people discover more and more complex things, or how the list of suspects changes throughout an investigation.
I hope I helped, feel free to ask for more.
The correct answer is A,D. Leonardo da Vinci is known for the sketches of the human anatomy and the Monaco Lisa and the last judgment.
The term Caliph means B. a Muslim ruler in the Islamic Empire