A) Quran is word of God written for all people, all time and all places and therefore it covers everything. It was memorized from day one as it came(it came circumstantially)It was written simultaneously also. If it is revised by the sinning people then it is not the word of God any more.If word of God(commandments) become outdated due to new time or new place or new people then it is not the word of God,because word of God should be good for all people,all times,and all places.
Today there are millions of Muslims who have memorized the entire book cover to cover.
IF HYPOTHETICALLY YOU TAKE ALL DIVINE BOOKS OF ALL FAITH FROM EVERY PLACE ON EARTH AND PUT THEM ON FLEET OF SHIP AND TAKE IT TO DEEP SEAS AND THEN DUMP ALL BOOKS THERE AND COME BACK,STILL ONLY BOOK YOU CAN PRODUCE WILL BE QURAN BECAUSE OF THE MEMORY.
Quran also is based on mathematical symmetry or balance so if you change words ,alter or revise the balance will fall apart .
Here are some examples of the mathematical balance.
SCIENCE CAN NOT EXIST IF IT IS NOT BASED ON MATHEMATICAL BALANCE OR FORMULAS BUT WHAT ABOUT THE DIVINE BOOK OF THE GREATEST SCIENTIST,I.E.GOD THE CREATOR OF THE UNIVERSE?
PROOF THAT QURAN IS UNCHANGED DUE TO ITS MATHEMATICAL BALANCE.,SAME AS TODAY AS WAS GIVEN TO PROPHET MUHAMMAD,AN UNLETTERED MAN WHO COULD NEITHER READ NOR WRITE.
https://medium.com/the-heart-of-quran/mathematical-miracles-of-quran-1318e5986c0b
GOD THROWS CHALLENGE TO READERS TO DISPROVE IT.AND SAYS YOU CAN DISPROVE IT IF YOU FIND CONTRADCITONS IN IT OR IF YOU MAKE LIKE THE SMALLEST CHAPTER IN IT(SMALLEST CHAPTER HAS ONLY 3 LINES)STILL THIS CHALLENGES IS NOT REPLIED FOR 1400 YEARS.