Which sentence is a good opening topic sentence for the following text ?

Read the excerpt from warriors don't cry. as we approached behind them, we could see only the clusters of white people that stretched for a distance of two blocks along the entire span of the school building. my mind could take in the sights and sounds only one by one: flashing cameras, voices shouting in my ears, men and women jostling each other, old people, young people, people running, uniformed police officers walking, men standing still, men and women waving their fists, and then the long line of uniformed soldiers carrying weapons just like in the war movies i had seen. which words create the mood in the excerpt? check all that apply.

Find the center and the radius of the circle with the equation: x^-2x+y^2+4y+1=0

What do you think is the greatest invention that you use today? explain in 4 sentences