Select the option that can be used as a one-word substitute for the given group of words.
A deal of agreement done in a company or firm.

The correct option is Contract.

Explanation:
Let us break down the meanings of the given words to understand why Contract is the most appropriate one-word substitute:

1. Contract: A formal, legal agreement made between two or more parties, companies, or firms that establishes enforceable rights and obligations.
2. Concurrence: The state of agreeing or having the same opinion, but not necessarily a formal business agreement.
3. Acceptance: The act of agreeing to an offer or proposal.
4. Conformity: Compliance with standards, rules, or laws.

Therefore, a deal of agreement made in a business or company setting is specifically called a Contract.