One of the arms of a male mollusc is used to transfer sperms into the female. Which is this animal?

Options

A. Pila
B. Loligo
C. Octopus
D. Teredo

Answer

To solve the question regarding which male mollusc uses one of its arms to transfer sperm into the female, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Group**: Understand that the question pertains to molluscs, which are a diverse group of invertebrates. They are characterized by their soft bodies and, in many cases, a hard shell.

2. **Recognize the Types of Molluscs**: Molluscs are divided into several classes, including gastropods, bivalves, and cephalopods. The question specifically refers to a male mollusc with a specialized arm.

3. **Focus on Cephalopods**: Among the molluscs, cephalopods (like octopuses, squids, and cuttlefish) are known for their advanced nervous systems and unique reproductive strategies.

4. **Identify the Arm Modification**: In male cephalopods, one of the arms is modified into a structure called a hectocotylus. This specialized arm is used to transfer sperm to the female during mating.

5. **Determine the Correct Example**: Among the options provided (Pila, Loligo, Octopus, Teredo), the octopus is well-known for having a hectocotylus. This arm is specifically adapted for sperm transfer.

6. **Conclude the Answer**: Therefore, the male mollusc that uses one of its arms to transfer sperm into the female is the **Octopus**.

### Final Answer:
The animal is **Octopus**.