An anchor ball need NOT be exhibited by an anchored vessel if she is __________.

Answer: B — less than 7 meters in length, and not in or near an area where other vessels normally navigate

The correct answer highlights a specific condition under which an anchored vessel is exempt from exhibiting an anchor ball. When a vessel is less than 7 meters in length and is anchored not in or near areas where other vessels typically navigate, it is not required to display the anchor ball. This rule recognizes that smaller vessels pose less of a hazard in low-traffic areas, thus simplifying regulations for these smaller crafts. In designated anchorage areas, the expectation is for vessels to adhere to visual signaling requirements regardless of their size. Similarly, the size condition of greater than 15 meters instead emphasizes a different level of responsibility due to increased visibility and potential risk. Lastly, a vessel that is stationary for less than one hour generally indicates a temporary state of being, which does not fulfill the criteria for being considered 'anchored' in a manner that necessitates signaling with an anchor ball. Thus, the rules focus on minimizing unnecessary requirements for small vessels in low-risk situations.