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: She became an assistant professor in 1983. Choices:  1. She was an assistant professor. 2. She has been in the field for long. 3. She was an assistant professor in 1980.

3