A certain strain of bacteria was found in the stomachs of ulcer patien

A certain strain of bacteria was found in the stomachs of ulcer patients. A medical researcher with no history of ulcers inadvertently ingested some of the bacteria and within weeks developed an ulcer. Therefore, it is highly likely that the bacteria strain induces ulcers.

Which one of the following, if true, most supports the argument above?

(A) People who have the bacteria strain in their stomachs have been found to have no greater incidence of kidney disease that do people who lack the bacteria strain.
(B) The researcher did not develop any other serious health problems within a year after ingesting the bacteria strain.
(C) There is no evidence that the bacteria strain induces ulcers in laboratory animals.
(D) The researcher is a recognized expert in the treatment of diseases of the stomach.
(E) A study of 2,000 people who do not have ulcers found that none of these people had the bacteria strain in their stomachs.