The correct option is D. can manufacture its food. Detailed Explanation:

1. Understanding Autotrophy:
2. Autotrophic organisms are those that can produce their own food using inorganic substances. The most common form of autotrophy is photosynthesis, where organisms convert light energy into chemical energy in the form of glucose.
3. Euglena's Characteristics:
4. Euglena is a genus of single-celled organisms that possess both plant-like and animal-like characteristics. They are primarily found in freshwater environments and can be classified as protists.
5. One of the key features of Euglena is its ability to perform photosynthesis due to the presence of chloroplasts, which contain chlorophyll. This allows Euglena to capture sunlight and convert it into energy, making it autotrophic.
6. Why Option D is Correct:
7. Since Euglena can manufacture its own food through photosynthesis, it is classified as an autotroph. This ability to synthesize food from sunlight and carbon dioxide is the defining characteristic of autotrophic organisms.

Why the Other Options are Incorrect:

• Option A: has flagella:
• While it is true that Euglena has flagella, which are whip-like structures that help in movement, this characteristic does not relate to its ability to produce food. Flagella are more about locomotion and do not contribute to the nutritional mode of the organism.
• Option B: has plant and animal features:
• Although Euglena does exhibit both plant-like (due to chloroplasts) and animal-like (due to its ability to move and consume food in the absence of light) features, this statement does not directly address its ability to manufacture food. The presence of these features does not define its autotrophic nature.
• Option C: is found in water:
• While Euglena is commonly found in aquatic environments, being in water does not inherently make an organism autotrophic. Many organisms, including heterotrophs (which cannot produce their own food), also inhabit water. Therefore, this option does not explain why Euglena is classified as autotrophic.

Summary of Key Points:

• Euglena is autotrophic because it can manufacture its own food through photosynthesis.
• It possesses chloroplasts that allow it to convert sunlight into energy.
• The presence of flagella, plant and animal features, or its aquatic habitat does not define its ability to produce food.
• Understanding the characteristics of autotrophic organisms is crucial for distinguishing them from heterotrophic organisms.

This thorough understanding of Euglena's characteristics and its classification as an autotroph will help you in your biology studies and exams.