Simile B and metaphor could be A or C they both are metaphors.
Add 100 and 20% you would get a total of 120%
Truth be told, it could be two. A would make sense in that the way the sentence is worded, the turtle herself seems weak. while C is also true to the word dragging as that would make it's movements awkward and difficult. I'd say your best bet would be C as turtles heavy backs and it's slowly speed would make the term "Dragging" make more sense.