In each question, one sentence is given in which certain words are in bold and numbered from A to E. Below the sentence are given five options with possible pairs of interchange of those bold words. Choose the pair(s) of words which are needed to be interchanged to make the sentence grammatically correct and meaningful.

Research (A)undermine that while the drugs may (B)improve concentration in people who are (C)diagnosed with ADHD, in those without that (D)condition the drugs may (E)suggests mental performance.