Hint: Cockroaches have mandibles. They are a pair of short structures situated on either side of the mouth. They are triangular in shape and hard due to the presence of a chitin layer. They are unjointed structures.
Complete answer: Mandibles are regarded as jaw or jawbones. These are present in arthropods mouthparts as crushing organs. The cockroach is an arthropod having three distinct regions namely the head, thorax, and abdomen. Its body is covered by a hard exoskeleton usually brown in colour that is made up of chitin. The cockroach’s mouth consists of a pair of appendages. The function of mandibles is to grasp, crush, or cut the food. Also, mandibles provide defence against predators as they are hard due to chitin composition. These are short and triangular structures. Each mandible in a cockroach has two types of teeth. These teeth are grinding teeth showing incisor teeth type characteristics. They help in the mastication of food. Cockroaches are omnivores and thus, can eat a wide range of food products. They also eat paper and wood scrapings. The labium of the cockroach is made by the fusion of the second pair of maxillae. The labium includes 3 segmented labial palps on either side. These are sensory structures that help to choose suitable food. The labium with labrum helps in holding the food in between maxilla and mandible while the grinding process. This is possible due to the grinding and incising function of mandibles. Further digestion of hard material is aided by the gut microflora.
Therefore, the right answer is option A.
Note: Cockroach is considered as one of the ancient insects dating back at least as far as the Carboniferous period, some 320 million years ago. They are very adaptable to their surroundings. They are insects of the order Blattodea, which also includes termites.