The correct answer is B, AWS Cloud9. AWS Cloud9 is a cloud-based integrated development environment (IDE) that enables developers to write, run, and debug their code through a browser interface. It includes features such as a code editor, terminal, and debugger, and supports collaboration among team members. It is designed to provide a seamless development experience by integrating with other AWS services like Lambda, Elastic Beanstalk, and EC2. The other options, while related to development and deployment processes on AWS, do not specifically provide the cloud-based IDE functionality required by the question.