Number 4 and why did you post this 3 times?
The answer would be the second option. The best reason for doing more background research after making an observation and before forming a hypothesis is to prevent making the same mistakes made in a prior experiment. It is to make sure that you are able to see the problems of a research and make an experimental design that will minimize the errors.
Homeostasis is the regulation of the internal environment of an organism.
Answer:
last one is the correct answer
Well I'm sorry if this is a tad bit late but ur answer issssss:
<em>Magnification power of ocular lens × power of the objective lens</em>
Hope this helped!