What two aspects should be inspected in a magnetic compass?

The correct choice highlights essential aspects of a magnetic compass's functionality. The clarity of the fluid is crucial because it ensures that pilots can see the compass card and read the heading accurately. If the fluid is cloudy, it can obstruct visibility and lead to misinterpretation of the compass readings, which could compromise safety during navigation. Additionally, having a legible compass card ensures that the markings are clear and that the pilot can effectively interpret the heading displayed by the compass. Both of these factors contribute significantly to the reliability and accuracy of the compass as a navigational tool, which is paramount for safe flying.

The other choices, while mentioning various components of the compass, do not emphasize critical aspects needed for proper functioning and safety. Therefore, the clarity of the fluid and legibility of the card are fundamental to ensuring effective and safe navigation.