Which sentence does not contain any errors in comma usage?

a.
oh i love to hear her voice.

b.
eating with your fingers can, certainly make things messy.

c.
after i arrive at the park for soccer practice, i check to see how muddy the field is.

d.
among all instruments, in the marching band, trumpets are usually loudest.

Aman lives on the twelfth floor of an apartment building. every morning he takes the elevator down to the lobby and leaves the building. in the evening, he gets into the elevator, and, if there is someone else in the elevator -- or if it was raining that day -- he goes back to his floor directly. otherwise, he goes to the tenth floor and walks up two flights of stairs to his apartment.

Create an accurate summary of the “goodbye” scene between marylin and her brother in “the cold equations”

How is dr. lanyon characterized in the excerpt? as friendly as arrogant as wise as mournful