The dependent variable in an experiment is a) the same in every experiment b) the variable scientists observe for changes c) the variable that is changed by the scientist d) the thing that is kept constant during the experiment

B) The variable scientists observe for changes

Explanation:

The dependent variable is the one that changes due to the independent variable.

The independent variable is one that scientists can modify and then observe how the dependent variable changes. This dependent variable may not be the same in every experiment and also may not be constant during the experiment (which discards the options A and D), those things can happen but is not the definition of a dependent varible.

The answer is B) The variable scientists observe for changes

Because the dependent variable cannot be modified directly by the scientist, since as its name says it depends on other factors in the experiment, so the dependent variable is the one observed to analyze the changes occurred.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

the force on the thing and the distance the force moves the thing