Thorn is a stem structure because it is

Options

A. develops from trunk
B. develops forms axillary bud
C. grows from external surface
D. is pointed

Answer

To solve the question "Thorn is a stem structure because it is:", we will analyze each option provided and determine the correct answer step by step.

### Step 1: Understand the nature of thorns
Thorns are modified structures found on certain plants. They are often sharp and pointed, which serves as a defense mechanism against herbivores.

**Hint:** Consider the function of thorns in plants and their origin.

### Step 2: Analyze the options
- **Option A: Developed from trunk**
- This option suggests that thorns originate directly from the trunk of the plant. However, thorns are not typically formed from the trunk itself.

**Hint:** Think about where thorns are commonly found on the plant.

- **Option B: Develops from auxiliary part**
- This option indicates that thorns develop from axillary buds. This is correct as thorns are indeed modifications of branches or stems that arise from these buds.

**Hint:** Recall the structure of axillary buds and their role in plant growth.

- **Option C: Grows from external surface**
- This option implies that thorns grow from the outer surface of the plant. While thorns are external, their origin is more specific than just growing from the surface.

**Hint:** Consider the developmental process of thorns in relation to plant anatomy.

- **Option D: Is pointed**
- While thorns are pointed, this characteristic alone does not define their structure as a stem. It is a descriptive trait rather than a developmental origin.

**Hint:** Focus on what makes a thorn a stem structure rather than just its appearance.

### Step 3: Conclusion
After analyzing all the options, the most accurate answer is **Option B: develops from auxiliary part**. This reflects the fact that thorns are modified branches or stems that arise from axillary buds.

### Final Answer
**The correct answer is Option B: develops from auxiliary part.**