**Answer:**

The correct answer is option 'B', Lupinus arcticus.

**Explanation:**

1. **Arctic Tundra:**
The Arctic Tundra is a type of biome characterized by extremely cold temperatures, low precipitation, and a short growing season. It is mainly found in the Arctic regions of the northern hemisphere, including Alaska, Canada, and Russia.

2. **Excavated Seed:**
The seed in question was excavated from the Arctic Tundra. Excavation refers to the process of uncovering and recovering artifacts or remains from archaeological sites. In this case, the seed was found buried in the frozen ground of the Arctic Tundra.

3. **Viable Seed:**
A viable seed is one that is capable of germinating and developing into a mature plant. The fact that the excavated seed was viable means that it had the necessary conditions and resources to resume growth after a period of dormancy.

4. **Germination after 10,000 years:**
According to the information provided, the seed germinated and flowered after an estimated record of 10,000 years of dormancy. This is an extraordinary feat considering the incredibly long period of time the seed remained dormant before sprouting.

5. **Lupinus arcticus:**
The correct answer, option 'B', states that the seed belongs to the species Lupinus arcticus. Lupinus arcticus, also known as Arctic Lupine, is a plant species native to the Arctic regions. It is a member of the legume family and is adapted to survive in the harsh conditions of the Arctic Tundra.

6. **Survival Mechanisms:**
Plants like Lupinus arcticus have various survival mechanisms that enable them to withstand the extreme cold and long periods of dormancy. These mechanisms include the production of antifreeze proteins, protective waxy coatings, and the ability to go into a state of dormancy until conditions are favorable for growth.

In conclusion, the seed excavated from the Arctic Tundra that germinated and flowered after 10,000 years of dormancy belongs to the species Lupinus arcticus. This plant species is adapted to survive in the harsh conditions of the Arctic Tundra and has mechanisms in place to ensure its survival during long periods of dormancy.