is this primary source or secondary source The main cause of the fall of the Byzantine

Question

Empire was the continuous attacks from
different external groups over time. The Seljuk
Turks and the Ottoman Empire invaded the
Byzantine Empire, which caused a big problem.
They threatened the empire's land and made its
military and economy weaker. As more invasions
happened, the Byzantines had a hard time
keeping control of important areas, which
caused their empire to slowly become weaker.
Moreover, these attacks made the Byzantine
Empire use up a lot of their money and army to
protect themselves, which made them more
susceptible to problems within their own
government and economy like political chaos and
lack of growth. In the end, the constant
attacks from outside forces were the most
important reason for the downfall of the
Byzantine Empire

Answer 1

This is not a primary source. It is a secondary source because it is an analysis or interpretation of historical events, rather than a firsthand account from someone who experienced those events.