Final answer:
Option (C), The misspelling of "candy" as "cade" is due to adding extra vowels, where a person mistakenly inserts an additional vowel, changing the word's spelling.
Step-by-step explanation:
The misspelling of the word "candy" as "cade" is an example of adding extra vowels. This type of allophonic variation occurs when a person mistakenly inserts an additional vowel into a word, altering its pronunciation and spelling. In the context of this question, the error likely arises from the understanding of how silent final changes the pronunciation of preceding letters.
For instance, a silent final can make the preceding soft, as in the word "geography," or mark a preceding as soft, which is evident in the words "lace," "price," and "twice." Nevertheless, in the case of "candy" becoming "cade," there is neither a nor a directly in front of the added , implying that the transformation is an instance of adding extra vowels.