Tags in Git are crucial for maintaining different versions of database scripts for various features. Tags provide a way to mark specific points in the version history, making it easier to reference and deploy specific releases of database scripts. This is especially useful when managing multiple versions of a database schema for different features or releases.

Git's branching model enhances Agile methodologies by facilitating parallel development. Multiple branches enable teams to work on different features simultaneously, promoting collaboration and faster delivery. The ability to isolate features in branches helps manage project complexity and supports Agile principles of adaptability and quick response to changes.

The correct option is a) commit-hash. This command allows you to apply the changes introduced by a specific commit onto your current branch. You need to provide the commit hash of the desired commit.

Subtree merge allows integrating an external project into another by merging in only the parts needed, maintaining separate histories. It's useful for combining projects without losing their individual version control contexts.

Git facilitates code reviews and quality assurance in large projects through features like branching and pull requests, which enable isolated code reviews. Additionally, it integrates seamlessly with automated testing tools and provides a detailed commit history and blame feature.

The correct option is git tag -l. This command lists all the tags in the Git repository. It's essential for getting an overview of available tags, especially in larger projects with numerous releases.

The git bisect command is used for binary search through the commit history to find the commit that introduced a bug. This helps in isolating the problematic commit efficiently.

After a version control failure, an enterprise is likely to focus on improving branching and merging strategies to prevent conflicts and enhance the overall stability of version control. Effective branching and merging are crucial for maintaining a reliable codebase.

In Git, each contributor has a local copy of the repository. The repository contains the entire project history and all the branches.

GitLab provides built-in CI/CD pipelines, allowing for automated testing and deployment, which is a unique feature compared to GitHub and Bitbucket.

Setting up efficient branching strategies is a critical aspect of scaling Git for enterprise. Clear and well-defined branching strategies help manage parallel development efforts, reducing conflicts and streamlining the integration process.

The best practice for securing sensitive data in a Git repository is to use tools like git-crypt, which encrypts and decrypts files transparently during a git clone or git pull. This ensures that sensitive information remains secure.