To solve this problem, we need to understand the concept of sexual dimorphism in cockroaches.$\newline$Sexual dimorphism refers to the differences in appearance between males and females of the same species.$\newline$In cockroaches, one of the key features of sexual dimorphism is the presence of anal styles.$\newline$• Anal styles are present only in male cockroaches.$\newline$• These are small, finger-like projections located near the anal cerci.$\newline$• Female cockroaches do not have anal styles.$\newline$Let's analyze the options:$\newline$• Option 1: Dark brown body colour and anal cerci are not specific to one gender.$\newline$• Option 2: Presence of anal styles is a characteristic feature of male cockroaches.$\newline$• Option 3: Presence of sclerites is common to both genders as they form the exoskeleton.$\newline$• Option 4: Presence of anal cerci is found in both males and females.$\newline$Therefore, the correct option is Option 2, as anal styles are specific to male cockroaches.