TOEFL Reading: ETS-TOEFL阅读机经 - Y17RP6365ZZ5F74FL$

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. A sentinel attempts to save as many closely related family members as possible, even if it dies while doing so. B. The group will not be able to pass their genes to future generations if a sentinel dies before alerting other family members. C. The genes of all members of the group will be passed to future generations even if a sentinel alerts only its close family members. D. Although a sentinel dies while alerting family members, it ensures that its genes will survive in future generations.