Read the following statements and select the incorrect ones.
(i) Circulatory system in arthorpods is of closed type.
(ii) Parapodia in annelids help in swimming.
(iii) Phylum Mollusca is the second largest animal phylum.
(iv) Aschelminthes are dioecious.

Options

A. a) (i) and (iii) only
B. b) (i) only
C. c) (iii) only
D. d) (iii) and (iv) only

Explanation

To solve the question, we need to evaluate each of the four statements provided and identify which ones are incorrect.

### Step-by-Step Solution:

1. **Evaluate Statement (i)**: "Circulatory system in arthropods is of closed type."
- The circulatory system in arthropods is actually of an **open type**, meaning that the blood does not circulate within defined blood vessels but instead flows freely through cavities called lacunae. Therefore, this statement is **incorrect**.

2. **Evaluate Statement (ii)**: "Parapodia in annelids help in swimming."
- Parapodia are indeed the locomotory structures in annelids that assist in swimming and movement. This statement is **correct**.

3. **Evaluate Statement (iii)**: "Phylum Mollusca is the second largest animal phylum."
- Mollusca is known to be the second largest phylum in the animal kingdom, with Arthropoda being the largest. This statement is **correct**.

4. **Evaluate Statement (iv)**: "Aschelminthes are dioecious."
- Aschelminthes (now often referred to as Nematoda) are indeed dioecious, meaning that they have distinct male and female organisms. This statement is **correct**.

### Summary of Findings:
- Statement (i) is **incorrect**.
- Statements (ii), (iii), and (iv) are **correct**.

### Conclusion:
The only incorrect statement is **(i)**. Therefore, the answer to the question is that the incorrect statement is **(i)**.