Sentence Correction

For at least two decades or more previous to when the Venetian artist Giovanni Battista Tiepolo died in 1770, he was the most admired painter in Italy.
A. For at least two decades or more previous to when the Venetian artist Giovanni Battista Tiepolo died in 1770, he was
B. For at least two decades before the Venetian artist Giovanni Battista Tiepolo died in 1770, he had been
C. For at least two decades or more before the Venetian artist Giovanni Battista Tiepolo's dying in 1770, he had been
D. When the Venetian artist Giovanni Battista Tiepolo died in 1770, for at least two decades previously he was
E. When the Venetian artist Giovanni Battista Tiepolo died in 1770, having been for at least two decades before that

only one I like is B.

"For at least two decades or more" is redundant, so A and C are out.

"When..." is not the right phrase, so D and E are out.

OA is B

Yup, I thought of B too