The correct answer is option 'B' - heart. In cockroaches, the allary muscles are associated or connected with the heart. Let's discuss the details below:

- **The Allary Muscles**: The allary muscles in cockroaches are a set of specialized muscles that are involved in the contraction and relaxation of the heart. These muscles are found within the abdominal cavity of the cockroach.

- **Function of Allary Muscles**: The allary muscles play a crucial role in the circulation of hemolymph, which is the insect equivalent of blood. These muscles help in regulating the pumping action of the heart, ensuring the proper flow of hemolymph throughout the body.

- **Heart of Cockroach**: The heart of a cockroach is a tubular structure located dorsally in the abdomen. It consists of a long, pulsating tube called the aorta, which is divided into several chambers or ostia. The ostia act as valves, allowing the entry of hemolymph into the heart during relaxation and preventing backflow during contraction.

- **Connection between Allary Muscles and Heart**: The allary muscles are directly connected to the heart and are responsible for its contraction and relaxation. When the allary muscles contract, they compress the heart, causing it to pump hemolymph into the aorta and out to the rest of the body. On the other hand, when the allary muscles relax, the heart expands, allowing the ostia to open and fill with hemolymph.

- **Coordination of Allary Muscles**: The contraction and relaxation of the allary muscles are coordinated by the nervous system of the cockroach. Nerve impulses from the central nervous system stimulate the allary muscles, causing them to contract rhythmically and maintain a steady heartbeat.

In conclusion, the allary muscles in cockroaches are connected with the heart. They play a vital role in regulating the pumping action of the heart and ensuring the proper circulation of hemolymph throughout the body.