What speed must you slow to if descending from 10,000 feet to 8,000 feet with an inbound speed of 300 KIAS?

When descending from 10,000 feet to 8,000 feet, it is essential to adhere to the regulatory airspeed limits. The general rule for aircraft during descent below 10,000 feet is that they must not exceed 250 KIAS, which is a standard restriction to maintain manageable air traffic flow, enhance safety, and minimize the noise impact on populated areas below.

In this scenario, if you are inbound at 300 KIAS, you need to decelerate to comply with this regulation as you approach 10,000 feet. The only airspeed from the provided choices that meets the requirement for descent at this altitude is 250 KIAS. This speed is not only compliant but also allows for safe handling characteristics as you transition to the lower altitude while preparing for any subsequent approaches or maneuvers.

Maintaining this airspeed helps ensure that the aircraft remains within regulatory standards while giving pilots adequate control and response capability as they continue their descent.