This is a boldface role question, so first find the main conclusion, then label each boldface portion by the role it plays relative to that conclusion. The manager's main conclusion is the unbolded recommendation: adopt the app at all depots before the holiday season. With that fixed, the two boldface portions fall into place. The first boldface is the colleagues' claim that the app would hurt productivity during a long adjustment period. The manager says 'I disagree,' so the first boldface is a position the argument opposes. The second boldface reports that drivers at the depot that has used the app for one month are already completing more deliveries per shift, which counts against the colleagues' worry and backs the manager's recommendation. So the second boldface is evidence offered against the first position. That is exactly choice (A).
(B) is wrong on conclusion status: the first boldface is the colleagues' claim that the manager rejects, not the manager's own conclusion, which is the unbolded recommendation. (C) gets the direction backward on both portions: the manager opposes the first position rather than adopting it, and the second boldface undercuts that position rather than supporting it. (D) attaches the right roles to the wrong portions, treating the first as supporting evidence and the second as the opposed position, which reverses the actual structure. (E) miscalls the second boldface the main conclusion; it is the evidence, and the conclusion is the unbolded recommendation. Each wrong choice fails on a clean structural error of role, direction, or conclusion status, so the answer is findable from the argument's structure alone.