Humanistic psychologist Carl Rogers contended that the most basic human motive is the .

the actualizing tendency.                        

Explanation:

Actualizing tendency: In psychology, the term "actualizing tendency" was proposed by one of the humanistic psychologists named Carl Rogers and is described as an organism's (all living beings) propensity to move forward to reach the fulfillment and completion of their potential. It states that the specific source related to the maturity and psychological growth is being encompassed within every organism.

In the question above, the given statement describes the actualizing tendency.

answer; in stage 6; morality of individual principles and conscience;