Option A is the correct answer because “immutable “ means unchanging over time or unable to be changed, which is the most suitable substitute for the given statement.
Option B is incorrect because “irrepressible “ means not able to be controlled or restrained, which is not the same as something that cannot be changed, hence it is incorrect.
Option C is incorrect because “irreparable “ means something that is impossible to repair or rectify, hence it is incorrect.
Option D is incorrect because “irrelevant “ means not connected with or relevant to something, which doesn’t match the given statement.