Which one of the following phyla is correctly matched with its two general characteristics?
(a) Arthropoda : Body divided into head, thorax and abdomen and respiration by tracheae .
(b) Chordata : Notochord at some stage and separate anal and urinary openings to the outsides
(c) Echinodermata : pentamerous radial symmetry and mostly internal fertilization
(d) Mollusca : Normally oviparous an development through as trochophore or veliger larva

Options

A. Arthropoda : Body divided into head, thorax and abdomen and respiration by tracheae .
B. Chordata : Notochord at some stage and separate anal anad urinary openings to the outsides
C. Echinodermata : pentamerous radial symmetry and mostyl internal fertilization
D. Mollusca : Normally oviparous an development through as trochophore or veliger larva

Answer

To determine which phyla is correctly matched with its two general characteristics, we will analyze each option one by one.

### Step-by-Step Solution:

1. **Option A: Arthropoda**
- Characteristics: Body divided into head, thorax, and abdomen; respiration by tracheae.
- Analysis: Arthropods do have a body divided into these three parts. However, while many arthropods (like insects) use tracheae for respiration, not all arthropods rely solely on tracheae; some use gills or other methods. Therefore, this option is **incorrect**.

2. **Option B: Chordata**
- Characteristics: Notochord at some stage; separate anal and urinary openings to the outside.
- Analysis: Chordates do possess a notochord at some stage in their development. However, not all chordates have separate anal and urinary openings; in some species, these openings are combined. Thus, this option is also **incorrect**.

3. **Option C: Echinodermata**
- Characteristics: Pentamerous radial symmetry; mostly internal fertilization.
- Analysis: Echinoderms typically exhibit pentamerous radial symmetry, but they can also reproduce through external fertilization, which is common in many species. Therefore, this option is **incorrect**.

4. **Option D: Mollusca**
- Characteristics: Normally oviparous; development through trochophore or veliger larva.
- Analysis: Mollusks are generally oviparous (laying eggs), and their development can indeed occur through trochophore or veliger larvae. This option is **correct**.

### Conclusion:
The only correctly matched phylum with its characteristics is **Option D: Mollusca**.

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