The correct answer is option 2: Their shape is distorted. When glaciers advance, they exert pressure on the surrounding landscape, including trees. As the glaciers move, they can push and deform the trees. This deformation can affect the growth of the trees and, subsequently, the shape of their rings. As a result, the rings of trees impacted by advancing glaciers may become distorted. This distortion can be observed in the width and spacing of the rings. It is important to note that glaciers can have different effects on trees, depending on the specific conditions and the degree of glacial advancement. However, in general, the pressure and movement of glaciers can cause the rings of trees to become distorted.