Field note reduction most commonly refers to which of the following actions?

Field note reduction primarily involves the process of manipulating recorded measurements to derive final results. This typically includes calculations to determine elevations, such as adding and subtracting back-sight and fore-sight readings to arrive at the precise elevation in a level-loop survey. Level loops are a crucial part of surveying as they help ensure the accuracy of elevation data by systematically balancing the readings taken at various points. This action of calculating differences between those readings is foundational in producing reliable elevation figures, making it a key aspect of field note reduction.

The other options, while relevant to surveying, do not specifically capture the essence of what is considered field note reduction. Recording weather conditions and crew details is important for documentation but does not directly pertain to adjusting numerical data for analysis. Summarizing observations is an overall reflection on the survey, yet it does not focus on numeric adjustments. Total distance calculations, while essential, do not encompass the broader range of data manipulation typically implied by 'field note reduction' as used in this context.