An internal shell is absent in

Options

A. Octopus
B. Sepia
C. Loligo
D. Both B and C

Answer

To solve the question "An internal shell is absent in," we will follow these steps:

### Step 1: Understand the Classification of Cephalopods
Cephalopods are a class of mollusks that include creatures like squids, octopuses, and cuttlefish. They are known for their advanced nervous systems and complex behaviors.

**Hint:** Familiarize yourself with the different types of cephalopods and their characteristics.

### Step 2: Identify the Presence of Internal Shells
In cephalopods, the presence of internal shells varies:
- Some cephalopods, like cuttlefish (Sepia) and squids (Loligo), have internal shells.
- Other cephalopods, like octopuses, do not have any internal shells.

**Hint:** Remember that not all cephalopods have the same anatomical features; focus on the specific examples.

### Step 3: Determine the Correct Answer
Given that the question asks where an internal shell is absent, we can conclude:
- The octopus is the only cephalopod among the mentioned types that lacks an internal shell.

**Hint:** Look for the cephalopod that is known for its lack of an internal structure, which is a key feature of octopuses.

### Final Answer
An internal shell is absent in the **octopus**.