What happens during a controlled experiment

a. no observation are made

b. many variables are changed

c. a factor called prediction is changed

d. the results of changing independent variable are observed

what is the correct answer
for this question

Ascientist wants to know how individual lions within a pride interact with each other in their own environment. to do this, the scientist sedates and tags all of the lions within a pride. then, he places several remotely-controlled video cameras near the lions' den and performs an observational field study. he collects continuous video footage over the span of one year, analyzes the video, and then forms conclusions based on his observations.