Which action does the precautionary principle advise to be undertaken while waiting for a reasonable estimate of Earth's carrying capacity to be made? 

A)  Live by the Earth principle. 
B)  Use material resources more efficiently. 
C)  Do not worry about population growth. 
D)  Continue to use energy resources at current rates.

The precautionary principle advises using material resources more efficiently while waiting for a reasonable estimate of Earth's carrying capacity to be made. This means that we should reduce our consumption of resources and use them more wisely to prevent any potentially irreversible damage to the environment. This approach will also help us to be better prepared for any unforeseen consequences that may arise from our current practices.