Final answer:
The prefix in the word 'pre-treatment' is 'pre-' and it means 'before'.
Step-by-step explanation:
The prefix in the word pre-treatment is pre-. A prefix is a word part attached to the beginning of a base word to create a new word with a different meaning. In this case, the prefix pre- means 'before'.
For example, in the word preheat, the prefix pre- means 'before', and the base word heat means 'to make hot'. When we combine them, we get the meaning of 'to make hot before'.
In the word pre-treatment, pre- indicates that the treatment is happening before something else.
Learn more about Prefixes in English words