The statement that is always true about the literary genre of satire is:
It employs an ironic or sarcastic tone.
While satire often includes humor and can have political elements, and while amusement is a goal, not all satire is necessarily intended to amuse every reader. Additionally, it doesn't inherently aim to confuse or make the reader feel uncertain, even if that might sometimes be a byproduct. Therefore, the use of an ironic or sarcastic tone is a defining characteristic of satire.