Final answer:
Pravastatin is the unique statin primarily excreted by the kidneys, which is important for patients with liver impairment.
Step-by-step explanation:
The only statin that is primarily excreted by the kidneys and undergoes renal excretion is pravastatin. Unlike other statins that are mainly metabolized by the liver, pravastatin is unique in that a significant portion of it is cleared from the body through the kidneys. This characteristic is particularly important when considering the use of statins in patients with liver impairment, as pravastatin might be a safer option in this population considering its different route of elimination.