Final answer:
A Constraint rule is used in a single-select configurable attribute to hide incompatible menu options, thus guiding users through a product configuration without the risk of choosing incompatible options.
Step-by-step explanation:
The rule used to hide menu options in a single-select configurable attribute is a Constraint rule. When setting up a configurable product, constraint rules ensure that incompatible options are hidden from the user to prevent them from selecting a combination of options that do not work together.
For example, if a laptop can either have an SSD or an HDD but not both, a constraint rule would be used to hide the HDD option once the SSD has been selected, and vice versa. This helps in preserving the integrity of the product configuration and improves user experience by guiding them through the configuration process without the risk of choosing incompatible options.