I would recommend that all professional bids be in writing, on formal letterhead and mailed or hand delivered to the company that you are proposing your bid for. All bids should be signed by both...
Correct answer typically implies there is one answer to the question. However, best answer can also be used if multiple answers COULD be correct, but one is better than the others.
The public is correct. plural and singular verbs can be tricky... but you use a singular verb with a singular noun, and a plural verb with a plural noun. For example: The person (singular) is...