Which of the following is true for opened sake?

The statement that opened sake should be consumed within two weeks is accurate because sake is a delicate beverage that can quickly deteriorate after being opened. Once a bottle of sake has been opened, exposure to air begins to affect its flavor and aroma due to oxidation. Although some varieties of sake can last longer under optimal storage conditions, the general recommendation is to consume opened sake within two weeks to fully enjoy its intended freshness and quality.

In contrast, while certain sake can be enjoyed at room temperature, the best practice for storing opened sake is to keep it in a cool place, preferably in the refrigerator. This helps to slow down the oxidation process and maintain its flavor profile. Consuming opened sake within a month may apply to some types but does not guarantee that the sake will retain its desirable characteristics beyond the two-week mark, making it less advisable than the two-week guideline. Thus, for peak quality and enjoyment, the two-week timeframe is the optimal recommendation.