While preparing to enter a Brazilian port, you see ahead a red and green horizontally- striped buoy. The upper band is red. What action should you take?

Correct Answer: Option D — Alter course to leave the buoy to starboard.

A horizontally-striped buoy with the top band red indicates a preferred channel to starboard when entering from seaward. Under the IALA system, you should treat this as a starboard-hand mark and pass it to leave it on your starboard side, ensuring you remain within the designated navigable channel.