The two nerve cords of cockroach are joined to each other at 

Options

A. terminal parts of segments
B. ganglia
C. nerves
D. not at all joined

Answer

To answer the question "The two nerve cords of cockroach are joined to each other at," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nervous System of Cockroach**: The cockroach has a complex nervous system that consists of a double nerve cord and ganglia. The nerve cords run along the length of the body and are responsible for transmitting nerve impulses.

2. **Identify the Structure of the Nerve Cords**: The two nerve cords are located ventrally (on the belly side) of the cockroach. They are connected at various points along their length.

3. **Learn About Ganglia**: Ganglia are clusters of nerve cell bodies that act as relay points for signals in the nervous system. In cockroaches, there are two main types of ganglia: the supraesophageal ganglion (which is part of the brain) and the subesophageal ganglion.

4. **Determine the Connection Point**: The two nerve cords of the cockroach are interconnected at the ganglia. Specifically, they are joined at the supraesophageal ganglion, which is located in the head region of the cockroach.

5. **Choose the Correct Answer**: Based on the understanding that the two nerve cords are joined at the ganglia, the correct answer to the question is "ganglia."

### Final Answer:
The two nerve cords of cockroach are joined to each other at **ganglia**.

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