The correct answer is B) The locking plates are used to prevent the fastening devices from vibrating loose. The primary function of the locking plates shown in the illustration is to prevent the fastening devices, such as bolts or screws, from becoming loose due to vibration. This is an important safety consideration for equipment used on ships and boats, where vibration can be a common issue. The locking plates help maintain the integrity of the connections and prevent potential failures or hazards that could arise from loosened fasteners. The other answer choices are incorrect because they do not accurately describe the purpose of the locking plates in the illustration. The transit washers, grounding straps, and abrasion resistors serve different functions that are not relevant to the primary purpose of the locking plates shown.