The volcanoes that occur near Earthquake belts and tectonic plate boundaries:

1. Caldera
2. Geysers
3. Pacific ring of fire
4. Midworld mountain belt

Mt. Vesuvius, Mt. Etna are located in the:

1. Circum Pacific belt
2. Mid-world Mountain Belt
3. Pacific Ring of fire
4. None of the above

Assertion (A): The lava and ash deposited during an eruption breaks down to provide valuable nutrients for the soil and thus create fertile soil.

Reason (R): Agricultural fields are covered with layers of volcanic ash and dust making them unsuitable for cultivation.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

The area marked brown colour on the map given above is referred to as the Pacific Ring of Fire. Why is it so called?