Please Help And NO LINKS OR U BE REPORTED! The difference between an observational study and an experiment is that

A.) in an observational study, only one group is studied, and in an experiment, two groups are studied.
B.) in an observational study, the researchers do not control treatment, and in an experiment, they do.
C.) in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.
D.) in an experiment, one group is studied over a short period of time, and in an observational study, the group is studied over a longer period of time.

For a school newspaper article, cienna conducted a survey to find out students’ favorite subjects. she polled all the students in mrs. lopez’s advanced dance class. why is her data likely to be skewed? honors dance students are more likely to enjoy dance than students in the general population, so dance may be overrepresented. cienna should have interviewed all the students in the school to get more accurate data. honors dance students are more likely to enjoy dance than students in the general population, so dance will be underrepresented. cienna should have interviewed only every other student in the class to avoid having too many people.

Gregory draws a scale drawing of his room. the scale that he uses is 1 cm : 4 ft. on his drawing, the room is 3 centimeters long. which equation can be used to find the actual length of gregory's room?

The sat and act tests use very different grading scales. the sat math scores follow a normal distribution with mean 518 and standard deviation of 118. the act math scores follow a normal distribution with mean 20.7 and standard deviation of 5. suppose regan scores a 754 on the math portion of the sat. how much would her sister veronica need to score on the math portion of the act to meet or beat regan's score?