The answer is most likely A because it looks like "over" is the only preposition used in any of these sentences.
Answer:
The Black Lives Matter protests that have followed the killings of George Floyd and Breonna Taylor by police officers remind Margaret Burnham of 1968.
Explanation:
At that time, the national response to the assassination of Martin Luther King Jr. combined with ongoing protests over civil rights and the Vietnam War to plunge an already divided nation more deeply into turmoil.
The coordinating conjunction among these is the word but.
However and although are subordinating conjunctions, not coordinating.
