Hola Temitope

In the case of geographical locations, "estar" is the correct verb to use because it refers to the location or position of a place, which is a condition rather than an inherent characteristic.

Even though the location of the Canary Islands in the ocean seems permanent, when talking about where something is located, "estar" is always used. For example, "Las Islas Canarias están en el océano."

It's a common point of confusion, and your reasoning makes sense, but the conventions of Spanish grammar favor "estar" for locations. I hope this clears up why "están" was the expected answer.

If you have any more questions or need further clarification, feel free to ask.

Saludos

Silvia