An igneous rock with large crystals cooled

1. slowly

2. quickly

3. underwater

4. in a volcano

The shape of an igneous rock is based on the time it takes for the rock to cool. The quicker an igneous rock is formed, the smaller the rock is going to be. If an igneous rock cools down slowly, It will be larger. Therefore an igneous rock with large crystals cooled down slowly. Therefore the answer is choice 1.

I think slowly is correct but if its wrong blame it on FuWei