Sentence Correction

The test results came back more quickly than the radiologist had expected them to, revealing the presence of benign tumors; fortunately, benign tumors, which are harmless, are non-progressive growths that do not metastasize and which can be excised before becoming malignant.


(A) benign tumors, which are harmless, are non-progressive growths that do not metastasize and which

(B) benign tumors are harmless non-progressive growths that do not metastasize and that

(C) benign tumors are harmless non-progressive growths that do not metastasize and which

(D) these harmless non-progressive growths do not metastasize, and benign tumors that

(E) these non-progressive, harmless growths that do not metastasize, are benign tumors that

Taken from Knewton:


[spoiler] OA:B...but why is E wrong?...apart from the fact that it is inverted.. [/spoiler]

(E) these non-progressive, harmless growths that do not metastasize, are benign tumors that

E is wrong because of missing AND between non-progressive and harmless.
this structure causes 'harmless growths that do not metastaize ' to be a non essential modifier.
Had there been an AND E might be correct.

can you please discuss C as well....between B and C difference is one that/which
and though B sounds parallel but please discuss the role of that in sentence B