According to paragraph 4, why was Griffith's experiment repeated in a test tube A. To provide additional support for the transformation of R-strain into S-strain pneumococci B. To establish whether or not the transformation of R cells was caused by something the mouse's body did C. To determine why the S-strain pneumococci somehow survived if they were in the presence of the R-strain D. To test the results of adding a cell-free extract to the mixture