On behalf of the jazz group Synco$-$Passion, their manager Raul agrees to a performance in the Quay Club on May $1.$ Portia, acting for Quay Club, sends a written copy of the agreement to Raul to be signed. Typically, businesspersons put their contracts in writing to

a$.$ create substance from form.

b$.$ ensure proof of the contracts" existence.

c$.$ practice their 'letters of credit.$\text{'}$

d$.$ obtain a check or other negotiable instrument.