Definition: In this task, you're given a statement, and three sentences as choices. Your job is to determine which sentence clearly disagrees with the statement. Indicate your answer as '1', '2', or '3' corresponding to the choice number of the selected sentence.
Input: Statement: Auditors should use cost models to look for discrepancies with the cost and schedule estimates established for an acquisition. Choices:  1. Auditors ought to search for cost and schedule discrepancies using cost models. 2. Auditors must avoid at all costs the use of cost models. 3. Cost estimates are usually too low while schedule estimates tend to be overly optimistic.

2