Which of the following experiments follow ethical standards? a.)performing test on animals when the information can be obtained in other ways. b.) experiments done to people who cannot protect themselves. c.) releasing contaminated contaminated waste into the water system. d.) research on animals in which the animal in which the animal experiences no fear or pain.

D.) Research on animals in which the animal experiences no fear or pain.

Explanation:

It is ethical to perform test on an animal such that the animal experiences no fear or pain.  

It is unethical to perform test on an animal when some other tests can be performed without the animal to get the desired results.  

Polluting the water resource with contamination is an unethical practice.  

People who are vulnerable cannot be subjected to experiments.  

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.