Why Is Placing a Seal Beside the Signature of a Guarantor

Why is placing a seal beside the signature of a guarantor signing a guarantee still enforced in modern-day Canadian society?

A) Absence of the seal renders the gratuitous promise in the guarantee unenforceable.
B) Absence of the seal suggests absence of the intention of the parties to contract.
C) Absence of the seal suggests an absence of acceptance of a firm offer.
D) Absence of the seal renders acceptance of the offer of guarantee unenforceable.