How have submersibles benefited ocean exploration?
a.
they allow exploration of arctic waters.
b.
they reduce the expense of ocean exploration.
c.
they allow the deep ocean to be explored.
d.
all of the above

The answer is c. They allow the deep ocean to be explored.

Thanks to submersible technologies, the exploration of the deep ocean is now possible. This brought a discovery of new deep-sea environments. It was hard to believe that in such deep-sea environment, without a light and with enormous pressure, the life may exist, but submersibles showed that it is possible.

The investiture controversy began as a power struggle between pope gregory vii (1072–85) and henry iv, holy roman emperor (1056–1106).[2] a brief but significant struggle over investiture also occurred between henry i of england and pope paschal ii in the years 1103 to 1107, and the issue played a minor role in the struggles between church and state in france, as well.by undercutting the imperial power established by the salian emperors, the controversy led to nearly 50 years of civil war in germany, and the triumph of the great dukes and abbots. imperial power was finally re-established under the hohenstaufen dynasty. historian norman cantor:

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