Before I say my opinion.
In Option A:
1) Can both parts of the laboratory be built at the same time?
2) If you are using the Plus Account: Can you build a bank with both parts of the laboratory at the same time?
No. Read the article again. That's the whole point of this discussion. In Option A you can only upgrade one of the two, because it is one building and you can't upgrade a building two times at the same time.
It is only possible to upgrade both speed and storage in Option B and only if you have Plus Account.