A、His notes were never found. B、His notes were left to his sons. C、His notes were found by other violin makers. D、There were not

Hundreds of violins are made every day. However, the finest were handcrafted by an Italian violin maker over two hundred and fifty years ago. The craftsman’s name was Antonius Stradivarius. Any one of his violins is worth more than ＄100,000 today.
    His instruments could reproduce tones as rich as those produced by the human voice. During his career he made over eleven hundred violins by hand, Those still in existence have become treasured possessions.
    Unfortunately, the secret of the Stradivarius violin died with its maker. During his lifetime Stradivarius kept his notes safely hidden. Even his two sons, who helped him in his workshop, did not know all the steps involved in each violin’s construction.
    Through the years, many experts have offered possible explanations for the unique tone of a "Strad". Some say it is the instrument’s shape and the harmony of its parts. Others suggest that the secret lies in the special properties of the wood that no longer exist. The most widely accepted supposition is the paint that the old master used to coat his instruments. Still, no violin maker has been able to fully reproduce the tone of Stradivarius’s violins.