In 1958, American satellites began to explore space, but it wasn't until astronauts began their own exploration in 1961 that humans got to go. You can just imagine the excitement on July 20, 1969, when American astronauts took their first steps on the moon! Space exploration was here to stay. A government program called the National Aeronautics and Space Administration (NASA) is responsible for all launches. Just like in 1958, today's launches take place at the Kennedy Space Center in Florida. Based on information from the text, in which year did astronauts first walk on the moon?

1958
1961
1969
1995

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.