Answer:
This is a primary source, namely a written one, because it derives directly from the past and its content hasn't been alternated.
Explanation:
Historians are dividing sources into primary and secondary. Primary sources are derived directly from the past, meaning that they are created at the time when some event happened. This is an example of primary source, as it is an original letter that one ruler sent to another one.
➡️The Habsburg Period in Spain is the collection of events between the 16th and 17th centuries. ✔️
➡️It begins with the Holy elected emperor of the Roman Empire, Fredrick the III.✔️
➡️The Habsburgs, of Austrian descent, was the dominant ruling family at the time; the most significant rulers are noted as Charles I and Phillip II.✔️
