Thank you for the opportunity to help you with your question!

No this is just a reasoning question. Since there are only three untrained rats then there is no possibility of getting 4 untrained rats since the rats are being placed in a different cage.

The answer is B as you indicated

However if the rats were being PICKED AND RETURNED IN THE SAME CAGE THEN b WOULD ALSO BE POSSIBLE

Please let me know if you need any clarification. I'm always happy to answer your questions.

Thanks for your help, but I was actually trying to figure out how many outcomes are possible for the experiment, as asked in 2. I'm not sure if you saw that part.

Sep 10th, 2015

Thanks for your help, but I was actually trying to figure out how many outcomes are possible for the experiment, as asked in 2. I'm not sure if you saw that part.