Sentence Correction

The neutrons residing in the nucleus of an atom have a mass virtually the same as the protons but without an electric charge.
(A) The neutrons residing in the nucleus of an atom have a mass virtually the same as the protons but without an electric charge
(B) The mass of the neutrons residing in the atom's nucleus is virtually the same as that of its protons, but the former do not have an electric charge
(C) Residing in the nucleus of an atom but without an electric charge, neutrons have virtually the same mass as protons do
(D) The neutrons and protons residing in the nucleus of an atom have virtually the same mass, but neutrons lack an electric charge
(E) Having virtually the same mass as protons do but lacking an electrical charge, neutrons reside in the nucleus of the atom

Answer: D

Can someone please explain what is wrong with C?

(A) The neutrons residing in the nucleus of an atom have a mass virtually the same as the protons but without an electric charge wrong comparision
(B) The mass of the neutrons residing in the atom's nucleus is virtually the same as that of its protons, but the former do not have an electric charge
(C) Residing in the nucleus of an atom but without an electric charge, neutrons have virtually the same mass as protons do
(D) The neutrons and protons residing in the nucleus of an atom have virtually the same mass, but neutrons lack an electric charge - correct
(E) Having virtually the same mass as protons do but lacking an electrical charge, neutrons reside in the nucleus of the atom

What is wrong with C?

What is wrong with C?

C is not parallel
C says: Residing in the nucleus of an atom but without an electric charge, neutrons have virtually the same mass as protons do---->"BUT" is a parallel marker so u need parallelism across "but"

ikaplan wrote: Can someone please explain what is wrong with C?

An introductory VERBing modifier must serve not only to modify the SUBJECT of the following clause but also to provide context for the VERB in the modified clause.
Sitting on a bench, John ate his lunch.
Here, sitting serves not only to modify John (JOHN is SITTING) but also to express how John ate (he ATE while SITTING).

C: Residing in the nucleus of an atom, neutrons have virtually the same mass as protons do.
Here, residing correctly refers to neutrons, but the connection between the VERBing action and the main action is unclear.
Residing in the nucleus does not seem to indicate how or why neutrons have the same mass as protons do.
Thus, the use of the VERBing modifier is inappropriate.