Which of the following cleanliness codes indicates the cleanest fluid?

The cleanliness codes in question refer to the levels of particulate contamination in hydraulic fluids and other lubricants. Each code represents particle counts based on specific particle sizes, usually measured in micrometers (µm). A cleanliness code is formatted as three numbers: the first indicates the number of particles greater than 4 micrometers, the second indicates those greater than 6 micrometers, and the third indicates those greater than 14 micrometers.

In the selection provided, the first code — 16/13/11 — reflects the lowest counts of particles in the categories specified. This means that the fluid associated with this code exhibits fewer particles of the critical sizes compared to the other codes listed. These lower particle counts indicate a higher level of cleanliness, which is essential in maintaining the efficiency and longevity of machinery and hydraulic systems.

The other codes exhibit higher particle counts, indicating a higher degree of contamination. The code that consists of 17/14/11 has a higher count for the first number, suggesting that it is not as clean as the first code. Similarly, the codes 20/18/16 and 23/19/17 show even higher levels of contamination across all three categories, making them the least clean in comparison. Hence