Final answer:
In Git, if the branch list for a rule is left blank, the rule applies to all branches. Answer A (Branches, all) is the correct choice.
Step-by-step explanation:
The statement refers to a configurable setting in Git, a version control system used for tracking changes in computer files and coordinating work on those files among multiple people. When configuring Git branching rules, if the list of branches where the rule is applied is left blank, it will apply to all branches. Therefore, the correct answer is A. Branches, all.