The main advantage of a model form contract is:
* The parties do not need to draft a complex contract from scratch each time,
* While still allowing some adaptation to suit the particular project.
This is exactly what option C states.
Options A and B can be features of many contracts (not unique advantages of model forms). Option D is true in practice (you still need legal advice for major changes), but it is not an advantage.
Reference: CIPS L4M3 Commercial Contracting - Model form contracts in construction and engineering.

The changes are made to the prime contract. They are also signed and approved by both parties. These changes are known as amendment (variation) to the contract. A contract amendment allows the parties to make a mutually agreed-upon change to an existing contract. An amendment can add to an existing contract, delete from it, or change parts of it. The original contract remains in place, only with some terms altered by way of the amendment.
Reference:
- Modify an Existing Contract with a Contract Amendment
- CIPS study guide page 26-28
LO 1, AC 1.1

Where the sale of goods is between two businesses in different Contracting States, then it is international and the CISG rules of law automatically apply unless they have been excluded. A contract clause stating that the contract is subject to the legal systems and courts of a particular country overrides or excludes the CISG rules, since the local rules of that country would apply instead.
So the answer should be Canada's legal system.
Reference: CIPS study guide page 49-52
LO 1, AC 1.2

KPIs that involve actual counts or quantifiable incidents are considered quantitative and use numerical data.
"Late deliveries" and "accidents or near misses" are measured in numbers, making them suitable for numerical performance tracking. The other options relate more to qualitative analysis or subjective feedback.
Reference:CIPS L4M3 Commercial Contracting Study Guide, Chapter 4, Section 4.3.2 - Quantitative KPIs and performance data.

Non-disclosure agreements (NDAs) are legally binding documents that protect confidential and proprietary information, including intellectual property, during pre-contractual discussions. NDAs ensure that sensitive data shared during early engagement or tender development is not misused.
Reference:CIPS L4M3 Commercial Contracting Study Guide, Chapter 3, Section 3.2.1 - Confidentiality agreements and intellectual property protection.