What is the rule concerning the use of inshore traffic zones?

The rule concerning the use of inshore traffic zones emphasizes that vessels should avoid using these zones when they are able to use designated traffic lanes. This is because inshore traffic zones can be narrower and pose greater risks, especially in areas where there may be commercial shipping traffic or fishing activities. By encouraging vessels to make use of traffic lanes whenever possible, the regulations help to ensure the safety of navigation and reduce the likelihood of collisions.

In the context of the other options, they imply different levels of restriction or use of inshore zones. For instance, suggesting that a vessel must use inshore zones at all times does not consider the need for safer navigation routes provided by traffic lanes. The idea that a vessel can only use inshore zones during emergencies fails to recognize that there can be appropriate situations for using them, but safety protocols must be followed. The notion that a vessel may only use inshore zones if accompanied by a pilot introduces an unnecessary requirement that could hinder normal operations in areas that are not particularly hazardous. Overall, option B aligns with the principles of safe navigational practices laid out in the COLREGs.