CCP = *TRIGGERED*
"Largest island in the Indian Ocean"
Hmm, Seychelles? Nope.
Can't be Mauritius, right? Nope.
Ummm, oh, what's that one that sits between Madagascar & the coast of Africa? Yeah, Comoros. That's GOT to be it! **Bzzzz**
Ah, no idea. Better move on.
Just because tectonic activity was involved does not mean it was *formed* by a volcano, it just means there might be a volcano located on that island. Those formed through subduction are likely to be prone to a lot of volcanic activity.