Which of the following is considered a defect of table grapes?

Waterberry is identified as a defect of table grapes due to the physiological condition that it indicates. Waterberry occurs when grapes absorb excessive water, resulting in a breakdown of the fruit's cells and causing it to appear swollen or translucent. This condition not only affects the aesthetic appeal of the grapes but also impacts their texture and flavor, leading to a poor eating experience.

In comparison, while brown spots, wrinkled skin, and discoloration may also be indicators of reduced quality or freshness, they do not specifically denote water-related physiological issues in the same way that waterberry does. Brown spots could be related to insect damage or fungal infections, wrinkled skin often indicates dehydration rather than overwatering, and discoloration can arise from various factors including sunburn or aging but doesn't specifically signify a defect in the same context as waterberry does. Thus, waterberry stands out as a defect associated with water management and physiological stress in grape cultivation.