International sporting events need not be fiscal disasters, the financial success of the 1992 Olympic Games demonstrates that fact.
(A) the financial success of the 1992 Olympic Games demonstrates that fact (incorrect: run-on sentence)
To connect two clauses, there should be a conjunction that is missing in option A.
(B) for example, the 1992 Olympic Games were financially successful (incorrect: placement error)
The underlined part is not an example of a disasters.
(C) like the financial success of the 1992 Olympic Games demonstrates (incorrect: comparison error)
Like is used to show similarity between two nouns instead of two clauses
(D) a fact demonstrated by the 1992 Olympic Games, which were financially successful (incorrect: modifier error)
A fact will become a modifier for disasters that is incorrect.
(E) as the financial success of the 1992 Olympic Games demonstrates (the best option)
x as y: events need, success demonstrates