What distinguishes the appearance of male German cockroaches?

Male German cockroaches can be identified by their distinctive coloration and physical characteristics. They feature a grayish tan color with two prominent dark stripes running longitudinally along the pronotum, which is the shield-like structure that covers their thorax. This color and stripe pattern is a key identifying feature of males, setting them apart from females and nymphs of the species.

In contrast, females tend to have a more rounded and broader abdomen to accommodate their reproductive organs, which contributes to a different overall appearance. This differentiation in body shape also aids in distinguishing between the sexes. Moreover, while male German cockroaches do possess wings, they are not a distinct identifying factor, as males have wings that are long and may extend beyond their abdomen, similar to females; thus, wing length alone does not help in identification.

Overall, the combination of color and the distinctive stripes on the pronotum is what makes option B accurate, as it directly describes the visual characteristics unique to male German cockroaches.