Water vascular system is the characteristic of which group of the following:
(a) Porifera
(b) Ctenophora
(c) Echinodermata
(d) Chordata.

Explanation

To determine which group has a water vascular system, we can follow these steps:

### Step 1: Understand the Water Vascular System
The water vascular system is a unique feature found in certain animal groups. It consists of a network of fluid-filled canals and tube feet that help in various functions such as locomotion, feeding, and respiration.

### Step 2: Analyze the Options
- **(a) Porifera**: This group includes sponges, which do not have a water vascular system. They rely on the flow of water through their porous bodies for feeding and respiration.
- **(b) Ctenophora**: Commonly known as comb jellies, this group also does not possess a water vascular system. They have a different method of locomotion using cilia.
...