Final answer:
The 250 knot speed restriction on the Olympia 6 arrival when landing north is most likely to apply after descending below 10,000 feet, following standard aviation regulations.
Step-by-step explanation:
The question relates to air navigation procedures on standard arrival routes, specifically the Olympia 6 arrival. In this context, the query is about the speed restriction imposed on an aircraft landing to the north.
When landing to the north on the Olympia 6 arrival, the relevant speed restriction that applies is 250 knots. Without specific charts or procedures for the Olympia 6 arrival, it's impossible to determine the exact point where this restriction comes into play. However, typically, speed restrictions can apply when departing a specific intersection or waypoint, after descending below a certain altitude, or upon crossing a navigational aid such as a VOR.
Generally, a common restriction for IFR arrivals is that all aircraft should reduce their speed to 250 knots when flying at or below 10,000 feet, in accordance with FAA regulations. This would likely be the correct answer, which is option (c).