Use the Following to Answer Questions

Use the following to answer questions
Scenario II
Scenario II is based on fabricated data inspired by the following study:
Kouchaki, M., Gino, F. & Jami, A. (2014) . The burden of guilt: Heavy backpacks, light snacks, and enhanced morality. Journal of Experimental Psychology: General, 143(1) , 414-424.
Weight and Guilt
Kouchaki and colleagues hypothesized that excess weight leads to emotional guilt. To that end, they asked participants to wear either a heavy backpack (12 pounds) or a light backpack (2 pounds) while sitting on a stool to "evaluate the quality of the backpack." In reality, the researchers were not interested in the participants' perception of the backpack's quality, but in how the weight of the backpack may subconsciously affect their behavior. As such, when the participants were leaving the laboratory they were told they may take a snack from a basket as a thank you for participating in the study. Two types of snacks were available: healthy and not healthy. The results revealed that 78% of the participants in the heavy backpack condition selected the healthy snack compared with only 48% of participants in the light backpack condition. The authors concluded that the type of snack the groups of participants chose indicates that an increase in weight causes one to experience feelings of guilt.
-(Scenario II) By randomly assigning participants to the heavy backpack condition or light backpack condition, the experimenters have:

A) reduced the likelihood that the participants will stay blinded to the research hypothesis.
B) minimized the influence of factors other than weight on their snack preference.
C) increased the external validity of the study.
D) ensured that only weight caused the participants' snack preference.