Which description best identifies the state of the batter when it needs to be changed?

The description that best identifies the state of the batter that indicates it needs to be changed is one that has a pink tint and is watery. A pink tint can suggest that the batter is either not properly cooked or that it has been contaminated, which is a serious food safety concern. Additionally, a watery consistency implies that the batter has broken down and is no longer providing the proper adhesion or coating for frying. This combination indicates that the quality and safety of the batter are compromised, thus necessitating its replacement to maintain high standards of food safety and product quality.

Other descriptions, such as being dark in color, might suggest overcooked product but isn’t as direct an indicator of needing to change the batter. A watery consistency alone could be a concern, but without the pink tint, it doesn't carry the same severity in terms of safety and quality. Similarly, a solid and crumbly texture might indicate a batter that has dried out or is past its prime, but it does not necessarily reflect the urgent need for change that is implicit in the pink and watery state.