Which one of the following statements about all the four of Spongilla, leech, dophin and penguin is correct ?

Options

A. Penguin is homoiothermic while the remaining three are poikilothermic.
B. Leech is freshwater from while all others are marine.
C. Spongilla has special collared cells called choanocytes, not found in the remaining three.
D. All are bilaterally symmetrical.

Explanation

To address the question regarding Spongilla, leech, dolphin, and penguin, we need to analyze each of these organisms and identify a common characteristic among all four.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- **Spongilla**: A freshwater sponge belonging to the phylum Porifera.
- **Leech**: A segmented worm belonging to the phylum Annelida.
- **Dolphin**: A marine mammal belonging to the order Cetacea.
- **Penguin**: A flightless bird belonging to the order Sphenisciformes.

2. **Examine Their Characteristics**:
- **Spongilla**: As a sponge, it is a simple multicellular organism that lacks true tissues and organs.
- **Leech**: It is a more complex organism with a segmented body and a true coelom.
- **Dolphin**: A highly complex organism with a developed nervous system, social behavior, and the ability to communicate.
- **Penguin**: A bird with feathers, a beak, and the ability to fly (in the evolutionary sense, as they are adapted to swimming).

3. **Identify Common Traits**:
- One of the most significant common traits among these organisms is that they all belong to the animal kingdom (Kingdom Animalia).
- They all exhibit some form of locomotion: Spongilla through water currents, leeches through muscular contractions, dolphins through swimming, and penguins through swimming and waddling.

4. **Conclusion**:
- The correct statement about all four organisms is that they are all members of the animal kingdom and exhibit some form of locomotion.

### Final Answer:
All four organisms (Spongilla, leech, dolphin, and penguin) are members of the animal kingdom (Kingdom Animalia).

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