Final answer:
The term 'Incorrigible' best fits the given phrase 'That which cannot be corrected', referring to a person or tendency that is not capable of being reformed.
Step-by-step explanation:
The word that can be substituted for 'That which cannot be corrected' is d. Incorrigible.
The term incorrigible refers to a person or their tendencies, which are not able to be corrected, improved, or reformed.
Here's why the other options do not fit:
- Unintelligible means not able to be understood.
- Indelible means something that cannot be removed or washed away.
- Illegible means not clear enough to read.
Incorrigible, therefore, is the answer that best fits the given phrase 'That which cannot be corrected'. Incorrect word: __________ Correct word: Incorrigible