It can be inferred from the passage that Van West notes the severe droughts which affected the Anasazi prior to the Great Drought primarily in order to
A． establish that enough food could have been grown to support the Anasazi's survival B． argue that the Anasazi's past behavior would indicate their likely future behavior in the case of a Great Drought C． suggest that the repetition of droughts was taking a cumulative toll on the fertility of the Plateau D． argue that the evidence which points to the existence of a Great Drought may actually be related to earlier droughts E． affirm the notion that the Great Drought may have been exponentially more severe than prior droughts