a~ shared characteristics are features or qualities that organisms or species have in common. 
 
c~ shared characteristics can be characteristics that existed in the common ancestor and still exist in modern organisms. 
 
d~ shared characteristics can be new characteristics that have been modified from what was found in the common ancestor.
i hope these are correct, if they aren't, i'm so sorry.
btw, i love your username!! 
rose from blackpink? Imaoo :D~