Final answer:
In Git, to create and checkout a new branch named 'greet', use the command 'git checkout -b greet'. This combines branch creation and checkout in one step.
Step-by-step explanation:
To create and checkout a branch named 'greet' in Git, commands from option B, git checkout -b greet, are used. To checkout the branch, you can use the command git checkout greet. However, you can also combine these two commands into one using the git checkout -b greet command, which creates and checks out the branch in a single step. This is a two-in-one command that performs the creation of the new branch and then checks it out in one step. If you wish to use separate commands, you would need to run git branch greet followed by git checkout greet, as listed in option A, which is also correct but more verbose than the combined command in option B.