Psychical, because you all you are changing is the state. You can simply reverse it by putting it in the fridge again.
Internal is very common for terrestrial animals
Global warming? In think that's it, but don't trust me.
Answer:
Independent variable: Salinity/Salt concentration
Dependent variable: hatching rate
Explanation:
As rightly stated in this question, INDEPENDENT VARIABLE, in an experiment, is the variable that the experimenter changes or manipulates in order to bring about a measurable response while the DEPENDENT VARIABLE is the variable that the experimenter measures in an experiment. Dependent variable as the name implies is dependent on the independent variable.
In this question where an hypothesis was given as follows: "Hatching brine shrimp is related to salinity (how salty the water is), then the greater the salt concentration, the higher the hatching rate". The hypothesis relates the independent and dependent variables i.e. it tells us how the independent variable affects the dependent variable.
Hence, according to the hypothesis, it is telling us how a change in SALINITY OR SALT CONCENTRATION will affect HATCHING RATE. Therefore;
Independent variable: SALINITY/SALT CONCENTRATION
Dependent variable: HATCHING RATE
