Which of the Following Methods Is Not One by Which

Which of the following methods is not one by which a company can execute a contract directly?

A) The two directors signing a contract without using a written seal.
B) The two directors cutting their skin with a pocket knife as they face the East, exchanging blood, and swearing on their mother's graves if this process is authorised by the company's constitution.
C) Affixing a common seal to a written contract and having two directors sign it.
D) Shaking hands.