The correct answer is option A. unchangeable.
"Immutable" refers to something that cannot be changed or altered. It is often used in contexts where it is important to emphasize the permanence or unchanging nature of an object, condition, or principle. In computer science, for example, an immutable object is one whose state cannot be modified after it is created.
In a broader sense, when something is described as immutable, it suggests that it is fixed, permanent, and resistant to change, whether by design, nature, or circumstance. This term underscores the concept of absolute constancy and invariability. Therefore, the correct answer is option A.