Rachel's parents used to pay her an allowance every week to feed the cats and to do a few other chores around the house. However, once her mother lost her job, her parents stopped giving her an allowance. Although Rachel quit making her bed every morning, she still continued to feed the cats. Which of the following best explains why Rachel continues to feed the cats?
1. With the extrinsic reward, the execution of the task relies on internal motivation.
2. Without the extrinsic reward, the task itself is eliminated.
3. With the intrinsic reward, the execution of the task relies on external motivation.
4. Without the extrinsic reward, the execution of the task relies on internal motivation.
5. Without the intrinsic reward, the execution of the task relies on external motivation.

What is the difference between an observational study and an​ experiment? choose the correct answer below. a. in an​ experiment, a treatment is applied to part of a population and responses are observed. in an observational​ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions. b. in an​ experiment, a treatment is applied to an entire population and responses are observed. in an observational​ study, a researcher measures characteristics of interest of an entire population but does not change existing conditions. c. in an​ experiment, a researcher measures characteristics of interest of a part of a population but does not change existing conditions. in an observational​ study, a treatment is applied to part of a population and responses are observed. d. in an​ experiment, a researcher measures characteristics of interest of an entire population but does not change existing conditions. in an observational​ study, a treatment is applied to an entire population and responses are observed.