The correct option is c, to grow new plants.
People in the Cahuilla tribe depended mostly on desert plants for their food. Acorns were popular as the oak trees could not grow in desert areas. The common food for these tribes included the fruit of mesquite tree. During the spring season mesquite blossomed which was eaten by boiling. During summers the pods which were green was used as a drink by grinding. After the pods dried they were eaten from the tree directly or made mesquite cakes which could be stored for long time. In all the conditions and seasons, not all the beans were harvested but a portion was left in the plant so as to let them grow into new plants and trees.