If it is completely impossible to put a contract in writing, which of the following would be the best substitute?
a.
having a friend witness the verbal agreement
b.
a video or audio recording of the verbal agreement
c.
the words “i promise” spoken in a verbal recitation of the contract
d.
a firm hand-shake between all those involved in the contract

b. a video or audio recording of the verbal agreement.

Step-by-step explanation: If it is not possible to have a written contract, then the best option is to record the audio contract or make a video as it can be available for an infinite duration of time whenever necessary. Options a, b and c will not work here because a friend witness may be absent at the time of need, words "I promise" and a firm hand-shake between the two persons involved will also not serve the purpose.

Thus, the best and the correct option is b. video or audio recording of the verbal agreement.