<span>Crust, mantle and core (core has 2 layers) </span>
A) The data to support his hypothesis, so he should investigate if the same change happens in the density of solid water.
A polar climate only has 2 subtypes. These are tundra climate (ET) and the ice cap climate (EF).
Both climate lack of warm summers. The average temperature is less than 10 degree Celsius. In a tundra climate, they experience at least a month of having above zero temperature compare to an ice cap which is always below zero.
