Answer:
Justify
Step-by-step explanation:
Verbs are words used to express actions, occurrences, and states of being.
Affixes are morphemes we add to the roots of words to change their meaning. A suffix is an affix we add after the root.
The root we have here is just, the meaning of which can be defined as moral, right or fair. Suffixes added to it here are -ice, -ify, and -ly. Out of them, the only one used to form verbs is -ify. Its meaning is to become or make (someone or something) become (something). This is why the verb to justify means to show or prove to be just or right.