If We Wanted to Determine Whether States That Pass Clean

If we wanted to determine whether states that pass clean air legislation (no smoking in public areas) are more likely to enact laws requiring motorcyclists to wear helmets than are states that had not passed clean air legislation, the unit of analysis would be:

A) the individual states.
B) the individual act of legislation.
C) passage or nonpassage of the clean air legislation.
D) the clean air legislation.
E) states that passed clean air legislation.