Explanation:

The mismatched pair in the given options is option B, which states that "First terrestrial plants to possess vascular tissues - Gymnosperms". This statement is incorrect because the first terrestrial plants to possess vascular tissues were actually the ferns, which belong to the Pteridophytes kingdom.

Reason:

1. Amphibians of plant - Bryophytes kingdom:
- Bryophytes are a group of non-vascular plants that include mosses, liverworts, and hornworts.
- They do not have true roots, stems, or leaves, and they require a moist environment to reproduce and grow.
- They are often found in damp places such as forests, swamps, and riverbanks.
- Therefore, the pairing of amphibians of plants with the Bryophytes kingdom is correct.

2. First terrestrial plants to possess vascular tissues - Gymnosperms:
- Gymnosperms are a group of seed-bearing plants that include conifers, cycads, and ginkgoes.
- They have vascular tissues, which allow them to transport water, nutrients, and sugars throughout the plant.
- However, they were not the first terrestrial plants to possess vascular tissues.
- The first terrestrial plants to evolve vascular tissues were the ferns, which belong to the Pteridophytes kingdom.
- Ferns have true roots, stems, and leaves, and they reproduce through spores.
- Therefore, the pairing of first terrestrial plants to possess vascular tissues with Gymnosperms is incorrect.

3. Water required for fertilization - Pteridophytes:
- Pteridophytes are a group of seedless vascular plants that include ferns, horsetails, and clubmosses.
- They require water for the fertilization process because their sperm cells need to swim through a film of water to reach the egg cells.
- This is known as water-dependent fertilization.
- Therefore, the pairing of water required for fertilization with Pteridophytes is correct.

4. Seeds enclosed in fruits - Angiosperms:
- Angiosperms are a group of flowering plants that produce seeds enclosed in fruits.
- They have true roots, stems, and leaves, and they reproduce through flowers.
- After fertilization, the ovary of the flower develops into a fruit, which protects the developing seeds.
- This unique characteristic sets Angiosperms apart from other plant groups.
- Therefore, the pairing of seeds enclosed in fruits with Angiosperms is correct.

In conclusion, the correct mismatched pair is option B, where Gymnosperms are incorrectly associated with being the first terrestrial plants to possess vascular tissues. The correct answer should be Pteridophytes, specifically ferns.