Which wine features delicate aromas, watermelon, and rhubarb flavors?

The correct choice is a wine known for its delicate aromas and flavors that include nuances of watermelon and rhubarb. This description aligns most closely with a style of wine that is often characterized by lightness and fruitiness, typically found in certain sparkling wines. The mentioned options present different types of wines, but the one that embodies these specific flavor profiles and aromas is most likely a sparkling wine that emphasizes freshness and subtle fruity notes.

The other options either represent full-bodied red wines or different types of sparkling wines that do not generally exhibit the same delicate fruit characteristics. For example, Cabernet Sauvignon is known for its bold, robust flavors rather than delicate aromas, making it a poor match for the question. Similarly, a Merlot/Cabernet blend typically presents deeper, richer fruit flavors instead of the light, refreshing qualities described.

Overall, the correct wine stands out due to its emphasis on lighter, more nuanced flavors, making it the best fit for the characteristics outlined in the question.