Cerro tololo is home to

a. world's highest navigable lake.

b. one of the world's largest observatories.

c. highest waterfall in the world.

d. largest rain forest in the world.

B. One of the world's largest observatories.

Explanation:

1. it was caused by feudalism

2. charlemagne used christianity as a major cornerstone for his rule. cloisters were built all over the empire to act as centers for the (re)population of the vast european wilderness.

3. the europeans feared the next raid every time chetak

i'm not so sure about #6. but i hope i you with the first 3.