series circuits, the current runs through all of them and they are conncted by the bulbs, so if you unscrew one, all light turn off
paralell, they are kinda independent, if you unscrew one, nothing happens to others
look at options
A. unscrew 1 light, if stay on, it's series, false, that's paralell
B. unplug, if stay on (then you have pozessed lights)
C. unsrew light, if stays on, it's parlell RIGHT ANSWER
D. cut strand in half (will cut power) if the plugged half stays on, then (pozessed circuit)
answer is C