Photosynthetic euglenoids are

Options

A. Obligate autotrophs
B. Facultative heterotrophs
C. Facultative autotrophs
D. Obligate heterotrophs.

Answer

To answer the question "Photosynthetic euglenoids are," we will analyze the options provided and understand the characteristics of euglenoids.

### Step-by-Step Solution:

1. **Understanding Euglenoids**:
- Euglenoids are a group of unicellular organisms classified under the kingdom Protista. They are known for their unique features, including the lack of a cell wall, which gives them a flexible shape.

2. **Identifying Key Characteristics**:
- Euglenoids possess chloroplasts, allowing them to perform photosynthesis. This means they can produce their own food using sunlight, but they also have the ability to absorb nutrients from their environment.

3. **Evaluating the Options**:
- **Option A: Obligate Autotrophs**: These organisms can only obtain energy from inorganic substances and cannot derive energy from other sources. This does not apply to euglenoids since they can also absorb nutrients.
- **Option B: Facultative Heterotrophs**: These organisms can perform photosynthesis when light is available but can also absorb organic compounds from their environment when light is not present. This accurately describes euglenoids.
- **Option C: Facultative Autotrophs**: This term suggests that organisms can only produce food in the presence of light. While euglenoids can photosynthesize, they are not limited to this mode of nutrition.
- **Option D: Obligate Heterotrophs**: These organisms must obtain all their food from other organisms. This is not applicable to euglenoids, as they can produce their own food.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option B: Facultative Heterotrophs**. This means that photosynthetic euglenoids can both produce their own food through photosynthesis and absorb nutrients from their environment when necessary.