Question

What distracted Emperor Charles V and Pope Leo X after 1521?

The Muslim threat on the eastern border of the empire and the building St. Peter’s Basilica.
The Celtic threat to the northern border of the empire and the building of the Temple in Jerusalem.
The Norse threat on the northern border of the empire and the building Wartburg Castle.
The Russian threat on the eastern border of the empire and the building St. Peter’s Basilica.

Answer 1

The first option.

Charles V was preoccupied by the Muslim (Ottoman) threat on his eastern frontiers, while Pope Leo X was absorbed with financing and building St. Peter’s Basilica (hence the indulgence campaign).