Which web service provides resizable compute capacity in the cloud?

Amazon EC2, or Elastic Compute Cloud, provides resizable compute capacity in the cloud, allowing users to easily scale their computing resources up or down based on demand. With EC2, users can launch virtual servers, known as instances, in various configurations to meet their specific needs for processing, storage, and memory. This flexibility is crucial for workloads that can change in resource requirements over time, such as web applications, data analysis, and machine learning workloads.

The service allows for the quick provisioning of instances, enabling users to respond promptly to changing workloads and demands. Additionally, EC2 instances can be tailored to different performance needs, offering a variety of instance types optimized for different tasks, whether they require high memory, compute capacity, or storage performance.

The other options do not primarily focus on providing general compute capacity in the same way. For example, Amazon EMR is specifically designed for big data processing using frameworks like Apache Hadoop and Spark, while AWS Batch manages batch processing. Amazon Kinesis is tailored for real-time data streaming and does not provide compute capacity in the traditional server sense. Thus, EC2 distinctly fulfills the requirement for resizable compute capacity in the cloud.