Homologous organs are

Options

A. Dissimilar origin and dissimilar structure
B. Dissimilar origin but similar functions
C. Similar origin with dissimilar function
D. None of these

Explanation

### Step-by-Step Solution

1. **Definition of Homologous Organs**:
Homologous organs are those that share a common ancestry, meaning they evolved from a common ancestor. Despite having different functions, their structural similarities indicate this common origin.

2. **Characteristics of Homologous Organs**:
- **Common Structure**: Homologous organs have similar structural features. For example, the forelimbs of humans, birds, and whales all have similar bone structures (humerus, radius, ulna, carpals, metacarpals, and phalanges).
- **Different Functions**: Although they have similar structures, the functions of these organs can vary significantly. For instance, the forelimb of a human is used for manipulation, a bird's wing is used for flying, and a whale's flipper is used for swimming.

3. **Examples of Homologous Organs**:
- **Forelimbs of Vertebrates**: The forelimbs of mammals (like humans), birds (like eagles), and reptiles (like bats) are classic examples of homologous organs.
- **Plant Structures**: Certain plant structures, like the thorns of a rose and the tendrils of a pea plant, can also be considered homologous as they evolved from a common ancestor but serve different functions.

4. **Incorrect Options**:
- **Dissimilar Origin with Similar Function**: This describes analogous organs, which are not homologous.
- **Dissimilar Origin with Dissimilar Function**: This does not fit the definition of homologous organs.
- **Similar Origin with Similar Function**: This is also incorrect as homologous organs have different functions.

5. **Conclusion**:
Homologous organs are defined by their common ancestry and similar structure, despite having different functions. This concept is crucial in understanding evolutionary biology.