As a wine ages, which of the following decreases?

C.

As wines age, their obvious fruity aromas (lemon, strawberry, cherry, etc.) decline. These so-called primary aromas, which come from the grapes themselves, are eventually replaced by the (hopefully stunning) bouquet of a well-aged wine. That bouquet is often nearly impossible to describe, representing as it does, the complex integration and coalescing of molecules and compounds over time.