While proceeding downriver (descending) you sight a red diamond-shaped panel with small, red reflector squares in each corner on the left bank. Under the U.S. Aids to Navigation System on the Western Rivers this is a __________.

Correct Answer: Option A — crossing daymark

A red diamond-shaped panel with red reflector squares is a crossing daymark on the Western Rivers. These marks indicate that the channel crosses from one bank to the other. Mariners must observe these carefully to adjust their heading and remain within the deepest part of the river channel.