TOEFL Reading: ETS-TOEFL阅读机经 - T337WM1YAY3T4D31L$

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. Precise and detailed diet planning is needed for times when neither fresh plants nor animals are available. B. Careful planning for storage is necessary to ensure that there is sufficient food during periods when plant foods are not available. C. Planning must be precise and detailed in order to ensure that their supply of plant food is safe. D. To survive periods of shortage, they need either reliable methods of storage or precise and detailed planning.