What Azure service is specifically designed to implement the NoSQL key-value model?

The appropriate choice for implementing the NoSQL key-value model is Azure Table Storage. This service is specifically designed to store large amounts of structured data, allowing for fast access through a simple key-value pair mechanism. It provides a schemaless design, which means that each entry (or row) can contain different sets of properties, making it very flexible for storing unstructured and semi-structured data.

In addition, Azure Table Storage is highly scalable and supports high availability and accessibility, which are key when dealing with NoSQL databases. This service is particularly useful for applications that require quick retrieval of large datasets without the complexity of a relational database.

Regarding other options, Azure Blob Storage is geared towards storing unstructured data, such as files and images, but does not provide a structured key-value model. Azure SQL Database is a relational database service that utilizes a structured query language (SQL) and is not intended for NoSQL storage. Azure Cosmos DB, while also capable of supporting a key-value model and providing multi-model database functionality, is more sophisticated than what is required specifically for the key-value model and adds various other capabilities that may be unnecessary depending on the use case.