Can i say this sentence, is this sentence grammatically correct. can i add it in my essay?

the sentence is:

after 4 years, a coincidence no one ever thought would happen, happened.

Which of the following is best written: 1. my favorite day of the year is july 24 my birthday 2. my favorite day, of the year, is july 24 my birthday 3. my favorite day of the year is july 24-my birthday 4. my favorite day of the year is (july 24) my birthday

What was the main reason for truman’s decision to drop the atomic bomb on japan? to shorten the war to punish japan to save american lives the answer is c!

The speaker in “the courage that my mother had” is a daughter friend grandchild mother