Which grape variety is often associated with the production of sparkling wine in the Loire Valley?

Chenin Blanc is indeed closely associated with the production of sparkling wine in the Loire Valley, particularly in areas such as Vouvray and Montlouis-sur-Loire. This grape variety is known for its high acidity and ability to retain freshness, which are essential characteristics for making quality sparkling wine. It can be vinified into various styles, including sparkling, dry, and sweet wines, allowing for versatility in wine production. The method frequently used in the Loire for sparkling wines is either the traditional method (the same method used in Champagne) or the méthode ancestrale, which contributes to the region's esteemed reputation for producing well-balanced and expressive sparkling wines.

In contrast, the other grape varieties mentioned have different primary associations. Cabernet Sauvignon is typically known for producing robust red wines, often found in Bordeaux and other regions with warm climates. Melon de Bourgogne is more commonly associated with Muscadet, a region in the Loire known for crisp white wines, rather than sparkling. Syrah, while prominent in regions like the Rhône Valley, is not specifically linked to sparkling wine production in the Loire. Thus, Chenin Blanc stands out as the correct choice for sparkling wine in this context.