Select the most appropriate one-word substitution for the given group of words. 

An ability to stay calm in difficult or dangerous situations.

Sangfroid

The most appropriate one-word substitution for the given group of words "An ability to stay calm in difficult or dangerous situations" is "Sangfroid."

Explanation of the options:

☀ Sangfroid: Sangfroid refers to the ability to stay calm, composed, and unflappable, especially in difficult or dangerous situations.

☀ Composition: Composition refers to the arrangement or combination of elements to form a whole, and it does not specifically denote the ability to stay calm in challenging circumstances.

☀ Steadfast: Steadfast means resolutely or unwaveringly firm and determined, indicating a person's strong commitment or loyalty, but it may not necessarily imply the ability to remain calm in difficult situations.