What command is used to install a package via the command line in Python?

The command "pip3 install package_name" is commonly used to install a Python package via the command line, particularly in environments where both Python 2 and Python 3 are installed. The "pip3" command explicitly refers to the package manager for Python 3, ensuring that the package is installed in the correct version of Python that you intend to use.

Using "pip" alone may also work on systems where Python 3 is the default version associated with the pip command. However, specifying "pip3" is a best practice in mixed environments, as it avoids ambiguity. This is why "pip3 install package_name" is often the preferred choice among developers who want to ensure compatibility with Python 3.

The other options do not provide the correct command format needed to install packages in Python environments. "install package_name" lacks the necessary context of specifying the package manager, and "pypi install package_name" misrepresents the command syntax for package installation.