Stem-and-leaf of Nicotine N = 25 Leaf Unit = 0.10 1 445 555??? 33999 l 2 NHHHHHDDDDD D a. Identify the variable. b. The brand of cigarettes called Now cigarettes has the lowest amount of nicotine per cigarette. According to the graph above, what is the nicotine level for each Now cigarette? c. The brand of cigarettes called Bull Durham cigarettes has the highest amount of nicotine per cigarette. According to the graph above, what is the nicotine level for each Bull Durham cigarette