The argument states that diabetics, who have trouble processing glucose, can eat ice cream from certain companies without discomfort because these companies do not add sucrose (a form of glucose). The conclusion depends on the assumption that the ice cream does not contain glucose from other sources in sufficient quantities to cause discomfort.
(A) suggests that these companies have replicated the taste of sucrose without adding substances that cause discomfort to diabetics. However, the taste is irrelevant to whether the ice cream causes discomfort, so this is not a required assumption.
(B) states that not all forms of glucose are equally likely to result in discomfort. While this might seem relevant, the argument focuses specifically on removing sucrose, not distinguishing between types of glucose. Thus, this is not a necessary assumption.
(C) points out that ice cream is not the only food to which glucose is added. This is unrelated to the argument, as it does not affect whether diabetics can eat the specified ice cream without discomfort.
(D) claims that apart from glucose, no other substances in ice cream commonly cause discomfort to diabetics. This might seem relevant, but the argument is specifically about discomfort caused by glucose, making this assumption unnecessary.
(E) states that glucose is not naturally present in the ice cream in quantities large enough to cause discomfort. This directly supports the conclusion because, if it were false, the argument would collapse—diabetics would still experience discomfort from naturally occurring glucose.
The correct answer is (E).