Answer: ensure proof of the contracts' existence
Explanation:
From the question, we are informed that on behalf of the rock group Uno, their manager Thalia agrees to a performance in Seaside Amphitheatre on July 4. Rex, acting for Seaside Productions, and then sends a written copy of the agreement to Thalia which was to be signed.
The main reason why businesspersons put their contracts in writing is in order to make sure that there is a proof regarding the existence of a contract. Without duly signing a contract, it means there is no proof and this can cause a lot of havoc in the future. The signature on contracts make it legitimate.
