A scientist employed by Head and Shoulders Shampoo wants to examine if Sulfate levels in shampoo contribute to drying out the scalp which could then lead to increased dandruff. Because the scientist believe that type of hair also plays a role in creation of dandruff, she divides the 600 volunteers into groups according to hair type. Of the 600 people, 240 have curly hair, 264 have wavy hair, and the remaining 96 have straight hair. The people within each group of hair type are randomly divided into three groups. People in Group 1 receive the standard shampoo with standard sulfate levels. The people in Group 2 are treated with higher sulfate levels, and the people in Group 3 are treated with lower sulfate levels. All other ingredients within the shampoos remain identical. After four months of using the shampoos the level of dandruff on each person's scalp are measured - no dandruff, mild dandruff, medium dandruff or extreme dandruff. the response variable. Identify the response variable. The level of dandruff on a person's head. The different levels of sulfate in the shampoos. The success rate of the shampoo with standard sulfate levels. The success rate of the shampoos with altered