The purpose of making traditional kimchi is to

Lactic acid bacteria are used when making pickles. Lactic acid is produced by lactic acid bacteria fermentation, which makes dishes have a special flavor. At the same time, lactic acid bacteria are anaerobic bacteria and do not need oxygen to decompose organic matter. Therefore, the pickle jar should be covered with a lid and sealed with a circle of water to prevent the outside air from entering. Otherwise, if air enters, it will inhibit the fermentation of lactic acid bacteria and affect the quality of kimchi. At the same time, capping can prevent the lactic acid produced in the pickle jar from volatilizing and increase the humidity of the air in the jar. See D.

So choose: D.