The step that a food worker must complete to prevent cross-contact is :
(D) washing hands and changing gloves before preparing an allergen-free meal
What is cross-contact?
Cross-contact is a food process whereby an allergen is transferred from one food to another accidentally, this occurs when foods come in contact with each other and their proteins get to mix up ( i.e. each food contains a little of the other).
Hence we can conclude that The step that a food worker must complete to prevent cross-contact is washing hands and changing gloves before preparing an allergen-free meal