The correct answer is (b) water storage.
Savanna is a tropical place located in which has high temperature round year.The savanna plants had adapted many adaptation to protect themselves from drought. They adapted a water storage organ called baobab.These are long cylindrical shaped trunk used to store water in dry conditions.This adaptation was necessary to store water for the times when there is a scarcity of water.These adaptation are necessary so that the trees can regrow in the next season after drought.