To what does the term 'constrict' refer?

The term 'constrict' specifically refers to the action of making something narrower or tighter. In various contexts, such as in physiology or mechanics, constriction often involves the reduction of the diameter of a tube or vessel, which can affect blood flow or airflow. By understanding that constriction indicates a decrease in size or volume, it is evident why the answer aligns with its commonly accepted definition.

In contrast, the other options represent actions that are opposite to constriction. Expanding indicates an increase in size or volume, loosening refers to making something less tight or more relaxed, and strengthening generally means to make something more robust or secure. Each of these terms conveys an opposite action, which helps clarify why narrowing is the accurate interpretation of 'constrict.'