Why should corked bottles be stored horizontally?

Storing corked bottles horizontally is primarily important to keep the cork moist and tight. When a wine bottle is laid on its side, the wine makes contact with the cork. This interaction prevents the cork from drying out, which can occur if the bottle is stored upright for an extended period. A dried-out cork may shrink or allow air to enter the bottle, leading to oxidation of the wine and ultimately degrading its quality. Maintaining a moist and properly sealed cork helps preserve the wine's characteristics for longer periods.

In understanding the other choices, it is clear that they do not address the primary function of horizontal storage regarding cork integrity. While allowing the wine to breathe is important for open bottles, it doesn't apply to sealed bottles stored horizontally. Avoiding exposure to light is also a relevant consideration, but it pertains more to the overall storage conditions rather than the positioning of the bottle itself. Lastly, facilitating sediment settling is a concern for some mature wines, but this does not necessitate horizontal storage, as sediment can settle on its own whether the bottle is upright or lying down.