Student 2 is right.
<h3>Constant variables</h3>
In research investigations, some variables should be kept constant across various experimental groups in order for the outcome of the investigation to be valid.
For example, in order to test how flatworms respond to different environments, one variable that should be kept constant is the flatworms. The flatworms to be used must be of the same species, sex, age, etc.
The investigator can then go ahead to divide the flatworms into two or more groups and then subject them to different environments. Other variables should also be kept constant in order to determine the effects that are only specific to the different environments only.
More on constant variables can be found here: brainly.com/question/474060
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Answer:
Geological, chemical, paleontological.
Explanation:
Geological evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics.
Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret.
It took some time for the current theory to be worked out.
There have been at least four major ice ages in the Earth's past.
Paleontological by their bones, remains
They don't have the same properties of a star fish
