A) "Year Event Occurred" is the explanatory variable because it is not the focus of the question when an event occurred just the correct answer to compare to, the estimated year is a guess based on the perceptions of the event.
B) A flat line along the x-axis
A) Because there's a positive correlation between union membership and strikes/lockouts, I used union membership to as the explanatory variable (it explains rises and falls in strikeouts)
B) Positive correlation
C) I checked out the positive correlation so I didn't need to use multiple scatterplots
D) There's a positive correlation between my variables
A) There's a positive correlation between population and Governor's salary
B) There are a few exorbitantly high salaries in the upper levels of 30k pop.