How can I use the requirements.txt file to manage the dependencies of my Python application in a Docker container?

To use the "requirements.txt" file to manage Python dependencies in a Docker container, follow the steps below:

1. Create a "requirements.txt" file listing all project dependencies and their versions.
2. In your Dockerfile, use a Python base image that matches your project's Python version.
3. Copy the "requirements.txt" file into the Docker image.
4. Inside the Dockerfile, use pip to install the dependencies from the "requirements.txt" file.
5. Build the Docker image with the Dockerfile.
6. Run containers from the image, ensuring that the dependencies are installed within the container.

This approach ensures that your Docker container includes the required Python dependencies specified, making it both portable and reproducible across different environments.