During the time period when saguaro cacti were evolving to their current form, there were years with very little rain. What likely happened to the saguaro cacti during the driest years?
a) The saguaro cacti managed to obtain the water they needed
b) Saguaro cacti with the shortest roots died
c) The saguaro cacti survived with less water than normal
d) The saguaro cacti grew longer roots