An experiment was conducted to investigate the the effectiveness of several insecticides. One-hundred insects of a particular species were put into a chamber and exposed to an insecticide for 15 seconds. The procedure was applied in random order six times for each of the four brands of insecticides (Brand A, Brand B, Brand C, Brand D). The number of dead insects out of 100 were observed for each chamber after exposure. To analyze the results, the investigators used ANOVA (Analysis of Variance). For this setting, what is the correct value for the degrees of freedom for the treatments