The I-V characteristics of three types of diodes at room temperature made of semiconductors X, Y, and Z, are shown in the figure. Assume that the diodes are uniformly doped and identical in all respects except their materials. If EgX, EgY, and EgZ are the band gaps of X, Y, and Z, respectively, then

• A. EgX > EgY > EgZ
• B. EgX = EgY = EgZ
• C. EgX < EgY < EgZ
• D. No relationship among these band gaps exists.