To test the effects of sunscreen on skin cancer, a group of scientists designed the following experiment: A large group of hairless mice were randomly separated into 3 groups (A, B, and C) by random assignment. For 360 days, Group A received daily doses of PABA 50 sunscreen, Group B receives daily doses of PABA 30 sunscreen and Group C receives no sunscreen. All of the mice are then exposed to two hours of sunlight per day for all 360 days. At the end of the experiment all mice are examined and cancerous skin lesions are counted and measured. a) Identify the experimental unit(s) or subject(s) of this experiment. Select all that apply. PABA 50, PABA 30 and absence of sunscreen Mice Number of days of exposure O Scientists O Number of hours of sunlight per day b) Identify the factors. Select all that apply. O Scientists Hours per day PABA 50, PABA 30 and absence of sunscreen Number and size of tumors Number of days O Mice X c) Identify the response variable(s). Select all that apply. Hours per day Number and size of tumors O Scientists Mice PABA 50, PABA 30 and absence of sunscreen O Number of days