Since $1987,$ airlines have been required to report to the Department of Transportation $($DOT$)$ the scheduled and actual arrival times of their domestic flights. Although the DOT collects detailed data about the actual minutes of delay incurred on each flight, it only counts a flight as being "late" if it arrives $15$ minutes or more behind schedule. The DOT issues monthly reports that rank airlines based on the percentage of their flights that are late under this definition and excerpts from these rankings are frequently reported in the media $($TV$,$ magazines, etc$).$

In $1996,$ TWA implemented employee bonus programs based explicitly on the TWA's performance in the government's ranking of on$-$time performance. Under this program, each TWA employee would receive a payment of between $$65$ and $$100$ in any month in which TWA is placed at or near the top of the DOT ranking. Figure A shows the distribution of delay time $($negative value indicates arriving earlier than scheduled time, and positive value indicates arriving later than scheduled time$)$ for TWA flights during $1987-1995.($Vertical lines in the figures indicate $15$ minute delay time$).$

$3-1.(1$ points$)$ Draw the distribution of delay time of TWA flights after the incentive plan $($bonus$)$ is introduced in $1996$ in Figure B $($For example, the dotted line shows when there is no change in the distribution$).$

$3-2.(1$ point$)$ The pattern in Figure B is most likely driven by gaming behavior.

a$.$ threshold

b$.$ rachet

c$.$ adverse selection

d$.$ loss$-$aversion