Which of the following statements is true about allosteric sites?

Allosteric sites are specific locations on an enzyme that are distinct from the active site, where substrates bind for a reaction to occur. The correct answer highlights that allosteric sites play a crucial role in enzyme allosteric regulation. When molecules bind to these allosteric sites, they can induce conformational changes in the enzyme, which can either enhance or inhibit its activity. This regulation allows for the fine-tuning of enzymatic activity in response to various conditions, making it a vital component of metabolic control.

In contrast, allosteric sites are not identical to active sites, nor are they limited to binding only inhibitors. They can also bind activators that enhance enzyme activity. While it is true that allosteric sites can affect the enzyme's catalytic activity, they do so by changing the shape of the enzyme rather than by directly binding substrates. Thus, option C is the correct choice, as it accurately describes the fundamental role that allosteric sites play in the regulation of enzyme activity.