What is the current value of the control variable of biosphere diversity?
a) Extinction rate: 50-500 E/MSY, BII (South Africa) 72%
b) Extinction rate: 100-1000 E/MSY, BII (South Africa) 84%
c) Extinction rate: 200-1500 E/MSY, BII (South Africa) 78%
d) Extinction rate: 75-750 E/MSY, BII (South Africa) 90%