Which plant group showed vascular tissue with integument megasporangium for the first time?

Options

A. Bryophyta
B. Pteridophyta
C. Gymnosperm
D. Angiosperm

Answer

To determine which plant group showed vascular tissue with integument megasporangium for the first time, we can analyze the options provided:

1. **Bryophyta**:
- Bryophytes are small, non-vascular plants, which means they do not possess vascular tissues. They reproduce through spores and do not have megasporangium or integuments. Therefore, this option is incorrect.

2. **Pteridophyta**:
- Pteridophytes are the oldest vascular plants and do possess vascular tissues. However, they also reproduce through spores and do not have integumented megasporangium. Thus, this option is also incorrect.

3. **Gymnosperms**:
- Gymnosperms are non-flowering plants that have vascular tissues and produce seeds that are not enclosed in an ovary (hence "naked seeds"). They do have integumented megasporangium, which contains megaspores. This is a key feature that distinguishes them from the previous groups. Therefore, this option is correct.

4. **Angiosperms**:
- Angiosperms are flowering plants that have seeds enclosed within an ovary. While they do have vascular tissues, they are not the first group to show integument megasporangium, as this feature is already present in gymnosperms. Hence, this option is incorrect.

Based on the analysis above, the correct answer is **Gymnosperms**, as they were the first plant group to show vascular tissue with integument megasporangium.

### Summary:
- **Correct Answer**: Gymnosperms