As the supply chain manager of a toy retail company, your task is to identify the best transportation modalities for importing toys from Beijing and Guangzhou, China, and distributing them to locations in Canada and the United States. This assignment focuses on multimodal design to enhance the efficiency of your supply chain. 10% of the toys are considered expensive, and 90% are lower-cost toys. 

Assignment Tasks: 

1. Describe the supply chain: Explain the import process from China and the distribution process to toy shops and retail stores in Canada and the US. Analyze key challenges and requirements. 

2. Multimodal Design: Define multimodal transportation and its benefits. Explain how intermodal transportation optimizes the supply chain by utilizing different modes. 

3. Evaluate transportation modals: Assess air freight, ocean freight, rail, and trucking considering cost, speed, reliability, capacity, and environmental impact. Analyze their suitability for specific stages of the supply chain. 

4. Multimodal Integration: Propose a multimodal transportation design that optimizes the supply chain. Discuss how different modals can be seamlessly integrated to improve efficiency. 

5. Recommendations: Recommend the most suitable transportation modals for each stage of the supply chain based on cost, speed, reliability, and sustainability. 

Justify your recommendations.