Answer:
Bicycles can influence the level of pollution positively due to no usage of gas, which exudes carbon dioxide into the atmosphere and contributes to the greenhouse effect. If more people rode bicycles everyday as opposed to public transportation or personal vehicles, pollution levels would fall significantly.
Formal.
As far as I know, there is no such thing as either standard or practiced diction. Informal is the way you communicate with your friends, for instance, which is not how you would write a thesis paper, legal document, etc.
He repeats the number 115 over and over in his mind, realizing he has said it before. Above him is a narrow crack in the rock. That's where the light is coming from.
Is a place where one lives ;a residence.
The answer would be (A) again because in a essay you are stating your points and you have a structure on how to do it and it must be consistent throughout the whole essay or its going to be choppy and you wont get a good grade. hopefully that made sense. The other answers wouldn't make sense. So go with (A)