If a wind direction is from 240° at 9 knots, which format would be used for transmission?

The correct format for transmitting wind direction and speed in aviation meteorology follows the standard that specifies the wind direction in degrees from true north, followed by the wind speed in knots without any additional indicators, as long as the wind is steady. In this case, "240" indicates the wind is coming from 240 degrees, and "09" denotes the wind is blowing at a speed of 9 knots.

The option chosen correctly adheres to this format since it only includes the wind direction and speed, with "KT" signifying that the speed is measured in knots. Other options add elements that are not standard for routine wind reporting. For example, including "G" would indicate gusting winds, which is unnecessary if the given information does not specify gusts. Similarly, using "N" would incorrectly imply a reference to magnetic north or some other additional information that is not required in this case. Therefore, the correct choice concisely portrays the wind's true characteristics without any extraneous notation.