What rating measures the ability of an element to effectively remove contaminants?

The efficiency rating is the correct choice as it directly relates to how well an element can remove contaminants. In engineering and environmental contexts, this rating quantifies the capability of a system, device, or component to function effectively in its intended purpose, which, in this case, involves contaminant removal.

Efficiency ratings take into account various factors, such as the quantity of contaminants removed in relation to the amount presented and the energy or resources used in the removal process. A higher efficiency rating indicates a greater ability to purify or clean a medium, which is crucial in applications like filtration, water treatment, and air purification.

In contrast, performance rating typically encompasses a broader scope, considering multiple aspects of operation, which may not focus solely on contaminant removal effectiveness. Durability rating assesses how well an item withstands wear, pressure, or damage over time, rather than its cleaning capabilities. Compatibility rating refers to how well different elements or systems work together, which is unrelated to the efficiency of contaminant removal. Thus, the efficiency rating is the most relevant measure in this context.