Which of the following guidelines is best practice for reusing brake fluid drained during bleeding operations?

A) allow it to settle first in a clear container to check for contaminants
B) filter through a strainer to remove particles
C) boil it to remove all moisture
D) never attempt to reuse any used brake fluid

Brake fluid is hygroscopic, meaning it absorbs moisture from the air, which can degrade its performance and potentially cause brake system failure. Reusing brake fluid that has been drained during bleeding operations is unsafe because it may contain contaminants and moisture that cannot be adequately removed through boiling, filtering, or settling. Therefore, the best practice is to always use new, uncontaminated brake fluid to ensure the safety and reliability of the brake system.