Which one of the followig phyla is correctlly matched with its two general characteristics

Options

A. `{:("Chordata " ,"Notochord at some"),("","stage and separate"),("","anal and urinary open"),("","ings to the outside"):}`
B. `{:("Echinodermata " ,"Pentameous radial"),("","symmetry and mostly"),("","internal fertilisation"):}`
C. `{:("Mollusca " ,"Normally oviparous"),("","and development"),("","through a trochophore"),("","or veliger larva"):}`
D. `{:("Arthropoda" ,"Body divided into head, "),("","thorax and respiration"),("","by tracheae"):}`

Answer

To determine which phylum is correctly matched with its two general characteristics, we will evaluate each option provided:

1. **Chordata**: The statement claims that chordates do not have a notochord at some stage and that they have separate anal and urinary openings to the outside.
- **Evaluation**: This is incorrect. Chordates do have a notochord at some stage of their life cycle, and while many have separate anal and urinary openings, it is not universally true for all chordates.

2. **Echinodermata**: The characteristics mentioned are pentamerous radial symmetry and mostly internal fertilization.
- **Evaluation**: This is also incorrect. Echinoderms exhibit pentamerous radial symmetry in their adult form, but their larvae typically show bilateral symmetry. Moreover, fertilization in echinoderms is usually external, not internal.

3. **Mollusca**: The characteristics state that they are normally oviparous and develop through trochophore or veliger larvae.
- **Evaluation**: This is correct. Mollusks typically reproduce by laying eggs (oviparous), and their larvae can develop through a trochophore or veliger stage.

4. **Arthropoda**: The statement claims that the body is divided into head, thorax, and respiration by trachea.
- **Evaluation**: This is partially correct. Arthropods do have a body divided into head, thorax, and abdomen (not thorax and abdomen). Additionally, respiration can occur through various structures, including trachea, gills, or book lungs, making this description incomplete.

**Conclusion**: The only option that is correctly matched with its characteristics is **Option 3: Mollusca**.

### Step-by-Step Solution:
1. **Identify the Phyla and Characteristics**: List the phyla and their respective characteristics.
2. **Evaluate Each Option**: Analyze the correctness of the characteristics for each phylum.
3. **Determine the Correct Match**: Identify which phylum has both characteristics correctly described.
4. **Conclude with the Correct Answer**: State that the correct answer is Option 3: Mollusca.