Which of the following ensures all parties understand the contract?

The option that ensures all parties understand the contract is the presence of clear and mutual agreements contained within the contract. This clarity is crucial because it defines the rights, responsibilities, and expectations of each party involved. When all terms and conditions are articulated plainly and agreed upon, the likelihood of misunderstandings decreases significantly.

Additionally, mutual agreement signifies that all parties have not only understood the terms, but have also consented to them, reinforcing that each party is on the same page regarding the contract's content. This mutual understanding is essential in avoiding disputes that can arise when parties have different interpretations of the contract.

In contrast, public announcements of contract terms do not guarantee understanding among all parties, as they might not reach everyone involved or may lack the context required for proper interpretation. Prior personal relationships can influence a contract's execution but do not inherently ensure that all parties understand the contract. Likewise, the length of the contract text doesn't correlate with clarity; a lengthy contract can be confusing, while a succinct contract can effectively convey essential terms.