(A) diagnosing and successful treatment, patients can grow to trust their physicians
first of all,there's parallelism error.
"diagnosing" isn't parallel with examination and treatment.
furthermore "patients can grow to trust their physicians" makes it sound like patients are the ones performing the actions mentioned .
(B) diagnosis and treatment, if successful, can lead patients to trust their physicians
"through...... can lead patients to trust their physicians"
makes no sense.
(C) and successful diagnosing and treatment, physicians can develop trust in their patients
parallelism error like A and changes the meaning.
(D) diagnosis and successful treatment, physicians can help their patients grow to trust them
pronoun ambiguity. "them" can refer back to physicians and patients both.
(E) diagnosis and successful treatment, physicians can develop in their patients growing trust
develop and grow both pretty much the same meaning here. sounds redundant to phrase the sentence this way.however, only option left and even awkard sounding answers are often right in GMAT. so IMO E