All the following are examples of homologous organs, except

Options

A. Arm of man and flipper of whale
B. Thorn of Bougaivillaea and tendril of Cucurbita
C. Eye of an octopus and eye of a mammal
D. Brain of frog and man

Answer

To solve the question "All the following are examples of homologous organs, except," we need to identify which of the provided options does not represent homologous organs.

### Step-by-Step Solution:

1. **Understand Homologous Organs**:
- Homologous organs are those that share a common ancestry, showing similar morphology, anatomy, genetics, and embryology, despite potentially having different functions.

2. **Analyze the Options**:
- We need to evaluate each option to determine if they are homologous or not.

3. **Option A: Arm of Man and Flipper of Whale**:
- These are homologous organs. Both have a similar bone structure (humerus, radius, ulna) but serve different functions (man uses it for manipulation, whale uses it for swimming).

4. **Option B: Thorn of Bougainvillea and Tendril of Cucurbita**:
- These are also homologous organs. Both structures are modified stems but serve different functions (thorn for protection, tendril for support).

5. **Option C: Eye of an Octopus and Eye of a Mammal**:
- These are not homologous organs. Although they perform the same function (vision), they have different structures and evolutionary origins (the octopus eye is a result of convergent evolution, not common ancestry).

6. **Option D: Brain of Frog and Man**:
- These are homologous organs. Both brains show similarities in structure and development, despite differences in complexity and function.

7. **Conclusion**:
- The only option that does not represent homologous organs is **Option C: Eye of an Octopus and Eye of a Mammal**.

### Final Answer:
The correct answer is **Option C: Eye of an Octopus and Eye of a Mammal**.