Abel had grown tired of working on the family farm and was considering moving away. However, his parents told him "If you'll stay and help us, we'll leave you the farm when we die." As a result, Abel decided to stay on the farm and worked there for the next twenty years. However, when his parents finally died Abel learned that they had left the farm to his brother, Mark. Abel filed suit against his parents' estate to enforce their promise of leaving him the farm. Which of the following is a true statement?
A) Abel gave no consideration for his parents' promise to leave him the farm, so their promise is not enforceable against the estate.
B) The work that Abel did on the farm before his parents made their promise is sufficient consideration to make their promise enforceable.
C) Abel's parents' promise is not enforceable because it was illusory.
D) Abel's parents' promise is enforceable under a promissory estoppel theory.

The authors of the paper "fudging the numbers: distributing chocolate influences student evaluations of an undergraduate course"† carried out a study to see if events unrelated to an undergraduate course could affect student evaluations. students enrolled in statistics courses taught by the same instructor participated in the study. all students attended the same lectures and one of six discussion sections that met once a week. at the end of the course, the researchers chose three of the discussion sections to be the "chocolate group." students in these three sections were offered chocolate prior to having them fill out course evaluations. students in the other three sections were not offered chocolate. the researchers concluded that "overall, students offered chocolate gave more positive evaluations than students not offered chocolate." indicate whether the study is an observational study or an experiment. give a brief explanation for your choice.