The correct answer is B) having a high affinity for moisture which requires it to be kept in a sealed container. Hygroscopic lubricants are those that readily absorb moisture from the surrounding environment. This characteristic is important in refrigeration compressors, where exposure to moisture can degrade the lubricant's performance and lead to issues like corrosion. To maintain the lubricant's effectiveness, it must be stored in a sealed container to prevent moisture contamination. The other options are incorrect because: A) loss of lubrication at higher temperatures is not a defining characteristic of hygroscopic lubricants, C) decreasing viscosity at low temperatures is not related to being hygroscopic, and D) toxicity is not a necessary property of a hygroscopic lubricant.