The difference between an observational study and an experiment is that

in an observational study, only one group is studied, and in an experiment, two groups are studied.

in an observational study, the researchers do not control treatment, and in an experiment, they do.

in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.

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.

Option b is true.

Step-by-step explanation:

Given that the difference between an observational study and an experiment is one out of the 4 options given.

Option I is wrong because in observation, also sometimes two groups are studied.

Option II is right, because observation is as it is observing what is happening but in an experiment they change certain things as required and study

Option III is wrong because in both cases, cause and effect is analyzed.

Option IV is wrong because both groups are normally studied for an equal necessary amount of time period.

spinning a 1, 2, or 3. option d.

step-by-step explanation: when spinning a number graph up to 4, and aiming for any number less than 3, that automatically eliminates the number 4. now you have two numbers to spin on that are less than 3, but the number 3 is included in this question because it's no greater of an number than itself. i hope this you : )

i can answer this question sweetie!

step-by-step explanation: