What happens to the proof of bourbon during the aging process?

During the aging process of bourbon, the proof can both increase or decrease, which is why the answer is B. The proof of bourbon is affected by the evaporation of alcohol and water through the barrel during maturation, a phenomenon commonly referred to as the "angel's share."

As bourbon ages, the barrel allows for some evaporation of alcohol, which can reduce the overall proof, especially in lower humidity environments where water evaporates more quickly than alcohol. Conversely, if the surrounding environment is more humid, the evaporation of water can be more significant, potentially increasing the proof as the alcohol content relative to the remaining liquid increases. This dynamic interplay means that proof can fluctuate and is influenced by the conditions in which the bourbon is aged, making both an increase and decrease possible.