The duckbill platypus is an exception to many mammals because it :

Options

A. lacks hair
B. is cold blooded
C. doesn't secrete milk
D. doesn't give birth but lays eggs

Explanation

**Step-by-Step Solution:**

1. **Identify the Duckbill Platypus**: The duckbill platypus is a unique mammal found in eastern Australia. It is known for its distinct features that set it apart from most other mammals.

2. **Understand the Characteristics of Mammals**: Most mammals are characterized by giving birth to live young and secreting milk to feed their offspring. However, the platypus has some exceptions to these traits.

3. **Evaluate the Options**:
- **Option A: Lacks fur** - This is incorrect because the duckbill platypus has thick fur.
- **Option B: Cold-blooded** - While the platypus is indeed cold-blooded, this is not an exception since there are other cold-blooded mammals.
- **Option C: Doesn't secrete milk** - This is also incorrect because the platypus has mammary glands, but it does not secrete milk in the traditional sense.
- **Option D: Doesn't give birth but lays eggs** - This is the correct option. The duckbill platypus is one of the few mammals that lay eggs instead of giving birth to live young.

4. **Conclusion**: The duckbill platypus is an exception to many mammals because it does not give birth but lays eggs.

**Final Answer**: The duckbill platypus is an exception to many mammals because it doesn't give birth but lays eggs.

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