The correct option is (a) reset. The git reset command is used to undo changes in the repository, including making a commit appear as if it never happened. It's important to note that using reset rewrites history, so caution should be exercised.

The Gitflow workflow model emphasizes parallel development by using feature branches. Each feature or bug fix is developed in its own branch before being merged back into the main codebase. This helps in managing and organizing complex development scenarios. Understanding Gitflow is crucial for teams working on projects with multiple features or bug fixes in progress simultaneously.

In an open source project, maintainers can use Pull Requests to efficiently review, discuss, and prioritize feature requests and bug reports submitted by contributors. Pull Requests provide a structured way to propose changes, discuss them, and merge them into the main codebase. This helps maintainers organize and prioritize contributions effectively.

The correct option, git reset --hard HEAD^, is used to undo the last commit completely. It discards changes and moves the HEAD pointer to the previous commit. git reset --soft HEAD^ preserves changes, git revert HEAD creates a new commit to undo changes, and git reset HEAD^ is for unstaging.

To push a specific tag in Git, the command is 'git push origin '. This command sends the specified tag to the remote repository named 'origin.'

A Git alias is a custom shortcut for a Git command. It allows users to create their own shorthand notation for frequently used Git commands, making the command-line interface more efficient and user-friendly. For example, you can create an alias 'co' for 'checkout' to save typing time.

Git hooks are scripts that can be triggered at different points in the Git workflow. The post-receive hook, in particular, is commonly used in DevOps pipelines to initiate automated processes like builds and tests after receiving new code.

Detaching a Git Submodule means it becomes independent, allowing changes without affecting the parent repository. However, it also implies that the submodule is no longer tied to a specific commit, making it susceptible to unintended changes. Managing submodule detachment is crucial for version consistency.

In open source development, developers typically fork a repository to create their copy, make changes, and then submit pull requests. This process allows project maintainers to review and merge contributions systematically.

While both GitLab and GitHub facilitate code collaboration, understanding the terminology and functionality differences in handling merge requests (GitLab) and pull requests (GitHub) is essential. GitLab uses the term "merge request" while GitHub uses "pull request," and there are nuanced differences in how they handle code reviews, approvals, and merging changes into the main branch.