Final answer:
The sentence that uses homophones incorrectly is 'The principle of the school makes decisions based on his principals.'
Step-by-step explanation:
The sentence that uses homophones incorrectly is:
d. The principle of the school makes decisions based on his principals.
In this sentence, the word 'principle' should be used to indicate the head of a school, while the word 'principal' should be used to refer to a basic truth or law.
Using the incorrect spelling creates confusion and changes the meaning of the sentence. It is important to be aware of homophones and use them correctly in order to effectively communicate in written language.