The correct answer is: B. Amazon SimpleDB
Amazon SimpleDB is a fully managed NoSQL database service that provides a simple API for storing and querying data. It is designed to be highly scalable, reliable, and easy to use. SimpleDB can be used to store any type of data, including strings, numbers, dates, and objects. It also supports indexing and data queries, which makes it a good choice for storing and querying large amounts of data.
CloudWatch is a monitoring service for AWS resources and applications. It provides a variety of metrics, alarms, and dashboards to help you monitor your AWS environment. CloudWatch is not a data store, and it does not support indexing or data queries.
Amazon CloudFront is a content delivery network (CDN) that delivers data, videos, applications, and APIs to customers globally with low latency, high transfer speeds, all within a developer-friendly environment. CloudFront is not a data store, and it does not support indexing or data queries.
Therefore, the correct answer is Amazon SimpleDB.