Which of the following clauses under an Open Cargo Policy is the MOST restrictive?

The Free of Particular Average Clause is indeed the most restrictive clause under an Open Cargo Policy because it limits the insurer's liability for partial losses. When this clause is included, the insurer will not cover losses unless they are due to total loss or specific risks that are generally accepted in a typical marine insurance policy. This means that if goods are damaged or lost partially, the insurer will not compensate the insured, making it a more limiting option.

In contrast, the With Particular Average Clause offers broader coverage by providing compensation for partial losses, although it may still have exclusions and requirements. The All Risk Form also offers comprehensive protection, covering a wide array of risks, even unforeseen events. Similarly, the Transportation Clause pertains to the actual transit of goods, but it does not have the restrictive nature of the Free of Particular Average Clause. Therefore, the Free of Particular Average Clause stands out as the most limiting provision within the context of cargo insurance.