Final answer:
The fluoroscopist's gonads must be shielded with a covering of 0.25 mm lead equivalent material for adequate protection against scatter radiation in fluoroscopy.
Step-by-step explanation:
The opening in the bucky tray cover that is directly in line with the fluoroscopist's gonads must be automatically covered with a material that provides adequate radiation protection. The correct option for such shielding is 0.25 mm lead equivalent material. This amount of lead is typically sufficient to protect against the scatter radiation expected in fluoroscopy. It's important to note that other materials like aluminum, even in higher thicknesses, are not as effective at providing the necessary protection against x-ray or gamma radiation as lead is. Therefore, it is imperative to use the right type of protective shielding to ensure safety from radiation exposure.