The correct answer is:

B. The transaction fails and all the changes are rolled back.

Explanation:
In Salesforce, the recursive transaction limit (also known as the "trigger recursion limit") is set to a maximum stack depth of 16. This means that if a series of recursive triggers or processes cause the stack depth to reach 16, the transaction will fail.

In this scenario, the Account trigger already hits a stack depth of 16, which is the maximum allowed. Once this limit is reached, Salesforce will throw an error, and the entire transaction will fail, rolling back all changes made during the transaction.

Therefore, the correct answer is B. The transaction fails and all the changes are rolled back.