Among the following, the most developed neural system is present in the

Options

A. Hydra
B. Vertebrates
C. Planaria
D. Insects

Answer

To determine which of the given options has the most developed neural system, we will analyze each option step by step.

### Step 1: Understand the Neural System
The neural system is responsible for coordinating and controlling body functions through a network of specialized cells called neurons. A more developed neural system typically allows for more complex behaviors and quicker responses.

**Hint:** Consider the complexity and efficiency of the neural systems in different organisms.

### Step 2: Analyze Hydra
Hydra is a simple organism that belongs to the phylum Cnidaria. It has a basic nerve net, which is a decentralized network of neurons. This means that Hydra has a very rudimentary neural system, lacking the complexity seen in more advanced organisms.

**Hint:** Think about the level of complexity in the nervous system of simple organisms like Hydra.

### Step 3: Analyze Planaria
Planaria are flatworms and belong to the phylum Platyhelminthes. They possess a more organized nervous system than Hydra, including a pair of cerebral ganglia (often referred to as a "primitive brain") and longitudinal nerve cords. However, it is still relatively simple compared to vertebrates.

**Hint:** Compare the nervous system structure of Planaria with that of more complex organisms.

### Step 4: Analyze Insects
Insects have a more developed nervous system than both Hydra and Planaria. They possess a central nervous system with a brain and a ventral nerve cord. Insects can exhibit complex behaviors, including flight, navigation, and social interactions.

**Hint:** Consider the capabilities and behaviors of insects that are enabled by their nervous system.

### Step 5: Analyze Vertebrates
Vertebrates, which include mammals, birds, reptiles, amphibians, and fish, have the most advanced neural systems among the options. They possess a well-defined brain and spinal cord, allowing for highly coordinated movements, complex behaviors, and advanced cognitive functions.

**Hint:** Reflect on the diversity and complexity of behaviors exhibited by vertebrates due to their advanced neural systems.

### Conclusion
After analyzing all the options, it is clear that vertebrates have the most developed neural system among the given choices. Therefore, the correct answer is **Vertebrates**.

**Final Answer:** Vertebrates have the most developed neural system.