At what percentage must the inner color of a watermelon be for it to be considered mature?

For a watermelon to be considered mature, the inner color must reach a certain intensity that indicates ripeness and optimal flavor. The threshold generally accepted in the industry is that at least 60% of the inner flesh's color must be indicative of maturity. This means that the flesh should have the deep, rich color that signifies it is fully ripe and sweet. If the watermelon only has 50% of this inner color, it may be deemed underdeveloped or immature, lacking the desirable characteristics of a mature watermelon.

Therefore, 60% is the level established to confirm ripeness and ensure that the fruit meets the quality standards expected by consumers. The other options provide lower or higher percentages, which do not align with this industry standard for maturity.