After it has taken over the function of the disabled white blood cells

boiled down to D and E,
D is much better than E b/c "by overwork" sounds awkward and "resulting pain" shows causal relation.

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.

a. 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
- Antecedent of IT is ambiguous. In the beginning of the sentence IT refers to LEUKEMIA. Hence Incorrect.

b. 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
- Antecedent of IT is ABSENT since nowhere SPLEEN is mentioned. Unnecessary use of Subjunctive Mood. Hence Incorrect.

c. 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.
- Antecedent of IT is Ambiguous. In the beginning of the sentence IT refers to Overwork. Hence Incorrect.

d. 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. - CORRECT

e. 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.
Unnecessary use of Passive Voice. Moreover, this option changes the original intent since it conveys that "Size of the Spleen" is result of "OVERWORK and PAIN". Hence Incorrect.

D for me,,,

spleen is overworked.... the meaning shud be conveyed properly...
thanks

Option D

The error with the sentence is that it sounds as if leukemia has taken over the function of disabled white blood cells

a. 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.Incorrect.Distorts the meaning
b. 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.Antecedent for the pronoun "It" is missing
c. 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.Too wordy so the meaning is not clear
d. 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.Correct
e. 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.pronoun "it" can point to spleen or white blood cells;antecedent is not clear

In option D what "that" is referring to. If its "overworked" then overworked did not triples in Size. Can anyone clarify on this.

D is the correct answer

This sentence "After it has taken over the function of the disabled white blood cells" should be followed immediately with the noun referred as "it"...so A, B & C are eliminated

D&E corrects the original error by replacing "it" with "the spleen"
"that is the first signal" is unclear and awkward
D is more clear and efficient than E

Here "that" is acting as a connector and not as relative pronoun.

A can be correct depending on how one interpret's the meaning. To me, it isn't 100% clear that the spleen should take over the function of white blood cells.

Meh question, IMO.

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.

a. 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.
Error in logical meaning of the modifier: The spleen has taken over the function of etc.. not the myeloid leukemia
b. 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.
The modifier modify now the spleen size. It should modify spleen. + "its pain" the possessive pronoun refers to size. Size can't feel pain. Illogical.
c. 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.
Overwork is now modified by the modifier
d. 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.
Correct, the modifier has been converted to a subordinate and spleen is the subject + It clearly refers to its antecedent spleen
e. 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.
Here there is a change meaning in the last part: Now the tripled size caused by overwork and pain are the first signal of leukemia because "that"modifies the entire precedent clause, not only pain