Answer:
Options
A. working in a controlled environment
B. recording all data and keeping it consistent
C. making sure that only one variable is being changed
D. performing the experiment in the same location
that the observations were done in
D is the correct answer, We do not need to an experiment where we first observed it, here is a great example. The sun fuses hydrogen atoms to make helium and energy in the form of light. scientists first observed this in the sun, but that doesn't mean we can only conduct nuclear fusion in the sun. we do it here on earth all the time.