I believe the answer is 3rd person
Actually..... all of them are correct!
The difference is whether the word "the orchestra" needs a plural or singular verb. In American English a singular verb is needed (so American English would only accept options a) and c) ) but in British English both forms are acceptable: so in British English all four sentences are correct.
Everybody on our block is going to the block party.
This is the correct answer!
