Natural killer cell activity was measured for subjects in several different groups. Assume that natural killer cell activity follows an approximately normal dis tribution. Researches want to know if the mean natural killer cell activity levels differ in the population between the groups. They decided to conduct an ANOVA test. How many groups are being compared based on the ANOVA table below? Source of Sum of Degrees of Mean Squares FStatistic Variation Squares Freedom 14150 62 \"I O 31 2 O 8 l Screenshot | OR