Which of the following match is correct?
(a) Cockroach-crustacea
(b) Pila-Pelecypoda
(c) Spider-arachnida
(d) Unio-gastropoda

Options

A. Cockroach-crustacea
B. Pila-Pelecypoda
C. Spider-arachnida
D. Unio-gastropoda.

Answer

To determine which of the following matches is correct, we will analyze each option one by one.

### Step-by-Step Solution:

1. **Option (a): Cockroach - Crustacea**
- Cockroaches belong to the class Insecta, which is part of the phylum Arthropoda. Crustacea is a different class within the same phylum that includes crabs, lobsters, and shrimp. Therefore, this match is incorrect.

2. **Option (b): Pila - Pelecypoda**
- Pila is a genus of freshwater snails and belongs to the class Gastropoda, not Pelecypoda (which includes bivalves like clams and oysters). Hence, this match is also incorrect.

3. **Option (c): Spider - Arachnida**
- Spiders belong to the class Arachnida, which is indeed a part of the phylum Arthropoda. This match is correct.

4. **Option (d): Unio - Gastropoda**
- Unio is a genus of freshwater mussels and belongs to the class Pelecypoda (or Bivalvia), not Gastropoda (which includes snails and slugs). Therefore, this match is incorrect.

### Conclusion:
The only correct match from the provided options is:
**(c) Spider - Arachnida**