A major difference between algae and most fungi is that the former possess:
(a) haustoria
(b) chloroplasts
(c) cellulosic cell walls
(d) both chloroplasts and cellulosic cell walls

Options

A. haustoria
B. chloroplasts
C. cellulosic cell walls
D. both chloroplasts and cellulosic cell walls

Explanation

To solve the question regarding the major difference between algae and most fungi, we can follow these steps:

1. **Identify the Nature of Algae**: Algae are primarily autotrophic organisms, meaning they can produce their own food through photosynthesis. This process requires chloroplasts, which are the organelles responsible for capturing light energy.

2. **Identify the Nature of Fungi**: In contrast, most fungi are heterotrophic, meaning they cannot produce their own food and instead obtain nutrients by decomposing organic matter. Fungi do not have chloroplasts.

3. **Examine the Cell Wall Composition**: The cell walls of algae are primarily composed of cellulose, which is a carbohydrate that provides structural support. On the other hand, the cell walls of fungi are made up of chitin, which is a different type of structural polysaccharide.

4. **Analyze the Options**:
- (a) Haustoria: These are specialized structures found in some parasitic fungi, not a distinguishing feature between algae and fungi.
- (b) Chloroplasts: Algae possess chloroplasts; fungi do not.
- (c) Cellulosic Cell Walls: Algae have cell walls made of cellulose; fungi have chitin.
- (d) Both Chloroplasts and Cellulosic Cell Walls: This option correctly states that algae possess both features.

5. **Conclusion**: Since algae possess both chloroplasts for photosynthesis and cell walls made of cellulose, the correct answer is (d) both chloroplasts and cellulosic cell walls.

### Final Answer:
(d) both chloroplasts and cellulosic cell walls