How many all-round white lights are required for an inconspicuous partly submerged object?

An inconspicuous partly submerged object is required to display two all-round white lights. This requirement serves to enhance visibility and safety, providing an indication of the presence of the object to other vessels, especially in conditions of reduced visibility. The two all-round white lights should be positioned so that they can be clearly seen from all directions, typically one light at each end of the object. This setup helps to prevent collisions by ensuring that other vessels can easily identify the object's outline and position in the water.

Having two lights, as specified in the correct answer, maximizes the object's visibility from various angles, which is particularly important for safety in navigation. Thus, the requirement of two all-round white lights is essential for any partially submerged object that may not be easily noticed by passing vessels.