'Which food did dinosaurs compete for?' would be impossible to test through observation. The last option.
Observation is a process of obtaining information about phenomena using any of the five senses. In other words, observations are a way of obtaining data for scientific purposes.
Why is the question about dinosaurs' food unanswerable by observations? This is basically because dinosaurs can no longer be observed in this our present world.
Dinosaurs are believed to have gone into extinction about 65 million years ago during the Cretaceous period. Thus, unless one can go back in time, there is no way to answer the question of which foods did dinosaurs compete for through observations.
More on observations can be found here: https://brainly.com/question/28041973
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