Diffuse and defuse — homophones or homonyms?

Which is correct?
Diffuse and defuse are often confused because they’re ________: words that sound the same but mean different things.
a. homophones
b. homonyms

Explanation:
Homophones are words that sound the same but are spelled differently and have different meanings. Diffuse and defuse sound alike but the first one means to spread something so it’s less concentrated. The second word, defuse, means to make a dangerous situation safe — or at least safer. As with removing the fuse from a ticking bomb.

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