A) it was "The Titanic" and his portrayal of romantic Jack Dawson that brought Leonardo De Caprio worldwide popularity and numerous awards.
B) Leonardo De Caprio's portrayal of romantic Jack Dawson in "The Titanic" brought him worldwide popularity and numerous awards.
C) Leonardo De Caprio earned worldwide popularity and numerous awards for his portrayal of romantic Jack Dawson in "The Titanic."
D) Leonardo De Caprio earned worldwide popularity and numerous awards based upon his portrayal in "The Titanic" of the romantic Jack Dawson.
E) it was his portrayal of romantic Jack Dawson in "The Titanic" that brought Leonardo De Caprio worldwide popularity and numerous awards.
1) Modifier issue ==> A,B, and E are out
2) between C and D, C is better and thus correct, In D...based upon his bla bla bla...seems wordy and awkward
IMO C...waiting for OA