Some researchers believe there is no such thing as true altruistic behavior because they believe that a. is unrelated to biological concerns b. is motivated by self-interest c. influences cognitive functioning d. is too uncommon to be observed

The correct option is B.
Some researchers believe that there is no such thing as true altruistic behavior because, they have observed that animals decide to exhibit helping behavior majorly because they have something to gain in doing so. When no reward is involved, animals tend to desist from sharing. 

The answer to your question, some researchers believe there is no such thing as true altruistic behavior because they believe that helping behavior., would be is motivated by self-interest . So the best answer to your question is letter B.

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