Final answer:
The protocol for amending the Canadian Constitution has existed since 1982 when the Constitution Act, 1982 was introduced, allowing Canada to amend its Constitution without British approval.
Step-by-step explanation:
The protocol for the amendment of the Canadian Constitution has existed since 1982. This was established through the Canada Act 1982, which includes the Constitution Act, 1982.
Prior to this, changes to the Canadian Constitution were made through the British Parliament, with the Statute of Westminster in 1931 granting full sovereignty to Canada, except for constitutional amendments.
The Constitution Act, 1982, allowed for Canada to amend its own Constitution without requiring approval from the British Parliament, thus making the correct answer to the question (b) 1982.