Question

threshold means :
great coolness and composure under strain
a region marking a boundary
wisdom in the management of public affairs
a disposition to behave forcefully and energetically

Explanation:

The word "threshold" commonly refers to a point or line of demarcation, a boundary. Among the given options, "a region marking a boundary" aligns with this common - usage definition. The other options describe different concepts: "great coolness and composure under strain" is more about a personality trait; "wisdom in the management of public affairs" pertains to governance - related wisdom; "a disposition to behave forcefully and energetically" is about a behavioral tendency.

Answer:

a region marking a boundary