TOEFL Reading: ETS-TOEFL阅读机经 - Q41BLN7U82OFG3R8L$

According to paragraph 3, the theory that meerkats' sentinel behavior is the result of kin selection is supported by the fact that A. sentinels warn the dominant males and females of the meerkat group first B. most members of a meerkat group are hereditarily related to each other C. immigrant members of the meerkat group will benefit from the sentinels' warnings D. only a small portion of a meerkat group serves as sentinels