Final answer:
A glass of industrial sludge is low in incentive value because although there may be a need like thirst, the negative aspects of the sludge make it undesirable and do not motivate consumption.
Step-by-step explanation:
The glass of industrial sludge from a polluted river would not be desirable to drink, even when very thirsty, because it is low in incentive value. This means the sludge is unappealing and does not motivate a person to want it, despite the existence of a need such as thirst. The contamination of water sources and the harmful substances in industrial sludge highlight serious environmental and health issues, reinforcing that the desirability of a substance is not determined solely by a need but also by the perceived benefits and risks associated with it.