In part A, the beak thickness changed due to the change in the sizes of the seeds. In part B, based on the graph pattern, the beaks size will further reduce.
The change in the average beak thickness:
Part A: It can be consider that in the wet years, the size of the seeds would be small, which perhaps would be easier for the birds with small beaks to break.
On the other hand, in the dry years, due to the production of the tough and large seeds, the small beaks of the birds fails to break them, thus, the thickness of the beaks need to increase as an adaptability.
On the basis of the graph, it can be seen that during the wet years, the beak thickness got reduced as there were small seeds to feed on. While in the dry years, the beak thickess increased due to the presence of large and tough seeds.
Part B: If the coming ten years appears to be wet, then via evolution the beak thickness will reduce further more, as the wet years will support the birds having less thick beaks.
Thus, there is a change in the thickness of the beaks due to change in the sizes of the seeds, and if the wet conditions prevails, the beaks with less thickness will be supported more.
Find out more information about the influence of conditions on the thickness of the beaks here:
https://brainly.com/question/9806758
