Which of the following words is closest in meaning to “Hermetic”?

Hermetic means sealed so that no air can get in or out.

• Correct answer - airtight: it has the same meaning as Hermetic.
• fast: quick - wrong, it does not mean the same as Hermetic.
• silent: making no sound - wrong, it does not mean the same as Hermetic.
• slow: not fast - wrong, it does not mean the same as Hermetic.