Answer:
They are based on social scientific research.
Explanation:
Generalisations are valid deductive inferences and it's applied in many disciplines. So, to generalize we need information that MUST be objective, that's why 'based on social scientific research' is the right answer, because scientific researches are objective, this means that the information is reliable to generalise. (Subjective is the opposite: not reliable)
Other answers are subjective and not qualified to support generalisations.