A team of scientists is interested in the effects of vitamin A, vitamin C, and vitamin D on the number of offspring born for a speci?c species of mice. An experiment is set up using the same species of mice. The mice are randomly assigned to three groups. Each mouse in the study gets the same amount of food and daily exercise and is kept at the same temperature. One group of mice gets extra vitamin A, another group gets extra vitamin C, and the remaining group gets extra vitamin D. The supplements are added to their food. The number of offspring are counted and recorded for each group.
(a) What is the response variable?
(b) What is the factor?