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: The most extensive study and analyses has been based on data from two prospective cohort groups, often referred to as the Harvard Six-City study (Dockery et al. Choices:  1. These cohort groups may not be as representative as initially thought. 2. Two prospective cohort groups have been the basis for most study. 3. The Harvard Six-City study is very minor and did not receive much analysis.

3