In which of the following organism the regulation of blood flow cannot be precisely regulated?

Options

A. Pila
B. Limulus
C. Scoliodon
D. Octopus

Answer

To determine which organism has a blood flow regulation that cannot be precisely controlled, we need to analyze the circulatory systems of the given organisms.

### Step-by-Step Solution:

1. **Understand the Types of Circulatory Systems**:
- There are two main types of circulatory systems in animals: open and closed.
- **Open Circulatory System**: Blood is not confined to blood vessels; it flows freely in the body cavity (hemocoel) and bathes the tissues directly. This system allows for less precise regulation of blood flow.
- **Closed Circulatory System**: Blood is contained within blood vessels, allowing for more precise regulation of blood flow through muscular contractions of the heart.

2. **Identify the Organisms**:
- The question provides several organisms, and we need to classify them based on their circulatory systems.
- **Pila (Apple Snail)**: Belongs to the phylum Mollusca, which typically has a closed circulatory system.
- **Octopus**: Also a mollusk, it has a closed circulatory system.
- **Scoliodon (Dogfish or Shark)**: A cartilaginous fish (phylum Chordata) that possesses a closed circulatory system.
- **Limulus (King Crab)**: A member of the phylum Arthropoda, which has an open circulatory system.

3. **Analyze the Circulatory Systems**:
- Since Pila, Octopus, and Scoliodon have closed circulatory systems, they can regulate blood flow precisely.
- Limulus, on the other hand, has an open circulatory system, meaning its blood flow cannot be precisely regulated.

4. **Conclusion**:
- The organism in which blood flow regulation cannot be precisely controlled is **Limulus (King Crab)**.

### Final Answer:
The correct answer is **Option B: Limulus**.