The suggested answer C (OSS) is correct.
Reasoning:
The scenario describes a rapid growth of video data exceeding the capacity of the existing ECS instance's data disks. The key requirements are scalable storage and quick access to historical data.

OSS (Object Storage Service) is designed for storing large amounts of unstructured data like video files. It offers:
- Scalability: OSS can scale to handle petabytes of data without requiring infrastructure changes.
- Cost-effectiveness: OSS typically offers lower storage costs compared to block storage (like ECS data disks), especially for large volumes of data.
- Durability and Availability: OSS provides high durability and availability, ensuring data is protected.
- Lifecycle Management: OSS supports lifecycle policies to automatically transition older video data to cheaper storage tiers or delete it after a specified period, optimizing costs.
- Easy Integration: OSS can easily integrate with other services for further processing or analysis of video data.

Reasons for not choosing the other options:

A. Container Service: Container Service is a platform for managing and running containerized applications. It does not directly address the storage capacity issue. While containers might be used to process video data, the underlying storage problem remains.
B. ECS: While adding more data disks to the ECS instance is a short-term solution, it's not scalable or cost-effective in the long run. The problem is the rapid growth of data, which would quickly exhaust the capacity of new disks as well. Moreover, managing and scaling ECS instances and their associated disks can become complex and expensive.
D. CDN: CDN (Content Delivery Network) is used for caching and delivering content to users from geographically distributed servers. It does not solve the problem of insufficient storage capacity for the rapidly growing video data. CDN is most useful for the live streaming or distribution of processed/archived video, not the primary storage of the raw video footage.

Therefore, OSS is the most suitable solution as it provides scalable, cost-effective storage with easy access and lifecycle management for historical video data.

The AI agrees with the suggested answer.

Citations:

Alibaba Cloud Object Storage Service (OSS), https://www.alibabacloud.com/product/oss