I will go with D on this..
After it has taken over the function of the disabled white blood cells, myeloid leukemia is often signaled by pain in the spleen, which may be so overworked that it triples in size.
- seems to indicate that myeloid leukemia has taken over the functions and it may be overworked and it triples in size.
After it has taken over the function of the disabled white blood cells, the spleen’s size may be tripled by overwork and its pain be a signal of myeloid leukemia
-- Here it seems to refer to spleen’s size. Which is wrong...
After it has taken over the function of the disabled white blood cells, overwork may cause the spleen to triple in size, and the resulting pain is often the first sign of myeloid leukemia
-- Here it seems to refer to overwork. Which is wrong...
After the spleen has taken over the function of the disabled white blood cells, it may be so overworked that it triples in size, and the resulting pain is often the first sign of myeloid leukemia
D is good
After the spleen has taken over the function of the disabled white blood cells, it may have its size tripled by overwork and pain that is the first signal of myeloid leukemia
- wrong formation