Which one of the following plants is monoecious

Options

A. (a) Cycas
B. (b) Papaya
C. (c) Marchantia
D. (d) Pinus

Answer

To determine which of the following plants is monoecious, we need to understand the definitions and characteristics of monoecious and dioecious plants.

### Step-by-Step Solution:

1. **Understand Monoecious Plants**:
- Monoecious plants are those that have both male and female reproductive organs on the same individual. This means that a single plant can produce both pollen (male) and ovules (female).

2. **Understand Dioecious Plants**:
- Dioecious plants, on the other hand, have male and female reproductive organs on separate individuals. This means that one plant will produce only male organs, while another will produce only female organs.

3. **Examine the Options**:
- **Option A: Cycas** (Gymnosperm)
- Cycas belongs to the gymnosperms category, which can be either monoecious or dioecious. However, Cycas is known to be dioecious, meaning it has separate male and female plants.

- **Option B: Papaya** (Angiosperm)
- Papaya is also dioecious, which means it has male and female flowers on different plants. Therefore, it cannot be the correct answer.

- **Option C: Marchantia** (Bryophyte)
- Marchantia is generally a dioecious plant, meaning it has separate male and female plants, making it an incorrect choice as well.

- **Option D: Pinus** (Gymnosperm)
- Pinus is a gymnosperm that is known to be monoecious. It has both male and female cones on the same plant, allowing it to produce both pollen and seeds.

4. **Conclusion**:
- After analyzing all the options, the only plant that is monoecious is **Pinus**.

### Final Answer:
The correct answer is **Pinus**.