A mammal in which both the sexes produce milk is

Options

A. Ornithorhyncus
B. Tachyglossus ( = Echidna )
C. Macropus
D. Didelphis .

Answer

To determine which mammal has both sexes producing milk, we can analyze the options provided:

1. **Understanding the Options**:
- **Ornithorhynchus**: This is a genus that includes the platypus, which is known for being one of the few mammals that lay eggs (oviparous). Notably, both male and female platypuses produce milk.
- **Tachyglossus**: This genus includes echidnas, which are also oviparous. However, in echidnas, only females produce milk.
- **Echidna**: As mentioned, this refers to the same group as Tachyglossus, where only females produce milk.
- **Macropus**: This refers to kangaroos and wallabies, which are marsupials. In marsupials, only females produce milk.
- **Didelphys**: This refers to opossums, which are also marsupials and similarly have only females producing milk.

2. **Identifying the Correct Answer**:
- From the analysis, the only mammal in the list where both sexes produce milk is **Ornithorhynchus** (the platypus). This is unique among mammals, as typically only females are known to produce milk.

3. **Conclusion**:
- Therefore, the correct answer is **Ornithorhynchus**.

### Step-by-Step Solution:
1. Analyze the options given in the question.
2. Identify the characteristics of each mammal listed.
3. Determine which mammal allows both sexes to produce milk.
4. Conclude that the correct answer is **Ornithorhynchus**.