Is the following an experiment or an observational study?

to examine whether eating brown rice affects metabolism, we ask a random sample of people whether they eat brown rice and we also measure their metabolism rate.

It's observational study

Explanation:

In observational study, researchers gather the data by simply observing the subjects without necessarily controlling the subjects. Inn experiment study, researchers will control the subjects. They wll determine what the subjects can or cannot eat, what substance they should take , etc.

From the example above, the researchers only ask the people (subject) about what they eat and measure it based on the answer. They do not control what type of nutrition that the people are taking, they gather the data based on the subjects' natural behavior.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.