The major difference between the mosses and ferns is:

Options

A. Ferns lack alternation of generation while mosses show the same
B. Mosses are facultative aerobes while ferns are obligate aerobes
C. Vascular bundles of ferns show xylem vessels while those of mosses lack it.
D. Sporophytes of ferns live much longer as compared to the sporophytes of mosses.

Answer

### Step-by-Step Solution:

1. **Identify the Groups**: First, we need to identify the two groups of plants in question: mosses and ferns. Mosses belong to the group called Bryophytes, while ferns belong to the group called Pteridophytes.

2. **Understand the Structure**:
- **Mosses**: The main plant body of mosses (Bryophytes) is thalloid and is primarily gametophyte-dominant. This means that the gametophyte stage is the most prominent and independent phase of their life cycle.
- **Ferns**: In contrast, ferns (Pteridophytes) have a vascular system and are the first terrestrial plants to possess vascular tissues. Their dominant phase is the sporophyte, which is independent and photosynthetic.

3. **Examine Alternation of Generations**:
- Both mosses and ferns exhibit alternation of generations, which is a life cycle that alternates between a haploid gametophyte and a diploid sporophyte. However, the significance of this alternation differs between the two groups.

4. **Evaluate the Options**:
- **Option 1**: Claims that ferns lack alternation of generations, which is incorrect as both mosses and ferns display this phenomenon.
- **Option 2**: States that mosses are facultative aerobes while ferns are obligate aerobes. This is not a major distinguishing feature.
- **Option 3**: Suggests that vascular bundles of ferns show xylem vessels. This is misleading as xylem vessels are actually found in angiosperms, not ferns.
- **Option 4**: States that the sporophyte of ferns lives much longer compared to the sporophyte of mosses. This is correct because the sporophyte in ferns is independent and photosynthetic, while in mosses, the sporophyte is dependent on the gametophyte for nourishment.

5. **Conclusion**: The major difference between mosses and ferns is that the sporophyte of ferns is independent and longer-lived compared to the dependent sporophyte of mosses.

### Final Answer:
The major difference between mosses and ferns is that the sporophyte of ferns lives much longer and is independent, while the sporophyte of mosses is dependent on the gametophyte and is not free-living.

---