Segmentation in the body is first observed in which of the following:
(a) Platyhelminthes
(b) Aschelminthes
(c) Annelida
(d) Arthropoda

Explanation

To solve the question regarding the first observation of segmentation in the body, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Segmentation**: Segmentation refers to the division of the body into repetitive segments or sections. This feature is significant in the classification of animals.

2. **Analyze the Options**:
- **(a) Platyhelminthes**: This phylum includes flatworms, which do not exhibit segmentation.
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