In the donner party, what caused the donner party from moving ahead to fort laramie as they had planned? a) one of the travelers fell sick with bilious fever and could not be moved. b)the weather had taken a sudden turn for the worst and the wagons could not hold up against the winds. c)they received news one of their group was needed back in illinois; they waited with him at the train depot d)they received news that the sioux indians were on the laramie plains preparing for war with the crow and snake tribes.