Answer:
B. assumption of conclusions without prior experimentation or observation.
Explanation:
In scientific investigation is quite important to demonstrate with facts, with observations, with numbers. All discoveries, new insights, new knowledge found in scientific investigation is based on a very careful finding of facts in a very systematic way of doing that to establish conclusions about the question to be answered and constantly looking for objective evidence.
For instance, one hundred years ago, some physicists found a crucial fact that support one of the predictions that Einstein posted regarding a phenomena described as curved space because of the effect that a massive object exerts around its surrounding space. In fact, that year of 1919, those physicists observed that light traveled around a massive start not in straight line but curving around start's space (a fact), of course, using telescopes, writing observations and quantifying them (a systematic way).
Einstein's theory (in this case, the famous General Relativity Theory) must be supported, at least in part, with the discovery of an important fact, and not because he assumed that it was 'true' without prior experimentation or observation but because some others experimental physicists took a 'secret' from Nature (objective evidence) and gave a crucial fact about what Einstein had predicted some years before.
But it is not a definitive fact, a definitive list, there will be some more facts to look for in order to support that theory (constantly looking) and, why not, some other scientist or scientists could find another one, make a new experiment, test another hypothesis or model that contradicts the whole theory or some part of it.