A chart with a scale of 1:45,000 is a __________.

Correct Answer: Option C — harbor chart

Chart scales are categorized by their intended use. Harbor charts are defined as having a scale of 1:50,000 or larger. Since 1:45,000 is a larger scale than 1:50,000, it provides the greater detail necessary for navigating within confined harbor waters, making it a harbor chart under standard hydrographic classification.