Final answer:
The root of the word 'disagree' is 'agree,' which is a free root because it can stand alone as a word in English without requiring any prefixes or suffixes.
Step-by-step explanation:
The root of the word disagree is 'agree.' A root can either be free or bound. A free root is one that can stand alone as a word in English, whereas a bound root needs other elements such as prefixes or suffixes to form a complete word. In the case of 'disagree,' 'agree' is a free root because it is a complete word on its own without the need for additional elements to convey a specific meaning. So, the root of the word 'disagree' is a free root.