Arachnida, Crustacea, Myriapoda and Insecta are classes of

Options

A. Platyhelminthes
B. Annelida
C. Mollusca
D. Arthropoda.

Answer

To determine the correct answer for the question "Arachnida, Crustacea, Myriapoda, and Insecta are classes of?", we can follow these steps:

### Step 1: Identify the Classes
First, we need to recognize that Arachnida, Crustacea, Myriapoda, and Insecta are all groups of organisms that belong to a larger classification system.

### Step 2: Understand the Options
The options provided are:
1. Platyhelminthes
2. Annelida
3. Mollusca
4. Arthropoda

### Step 3: Analyze Each Option
- **Platyhelminthes**: This phylum includes flatworms and has classes such as Cestoda, Trematoda, and Turbellaria. None of the given classes belong here.

- **Annelida**: This phylum includes segmented worms and has classes like Polychaeta, Oligochaeta, and Hirudinia. Again, none of the given classes belong here.

- **Mollusca**: This phylum includes mollusks and is divided into classes such as Gastropoda, Bivalvia, and Cephalopoda. The given classes do not fit here either.

- **Arthropoda**: This is the phylum that includes invertebrates with jointed legs. The classes Arachnida (spiders, scorpions), Crustacea (crabs, lobsters), Myriapoda (centipedes, millipedes), and Insecta (insects) all belong to this phylum.

### Step 4: Conclusion
Based on the analysis, the correct answer is **Arthropoda**. Therefore, Arachnida, Crustacea, Myriapoda, and Insecta are classes of the phylum **Arthropoda**.

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