Multiple Trait Analysis (Beak Width and Beak Depth)on the Medium

Multiple Choice

Multiple trait analysis (beak width and beak depth) on the medium ground finch,in response to the drought of 1976-77,has generated the three-dimensional graph,shown in the accompanying figure.If the blue triangles represent fitness levels for the quantified parameters,then the birds showing the greatest fitness should have ________.

A) deep, wide beaks
B) deep, narrow beaks
C) shallow, wide beaks
D) shallow, narrow beaks