Which statement best describes reserves? 

A)  They are identified and subeconomic. 
B)  They are identified and profitably extractable. 
C)  They are unidentified and subeconomic. 
D)  They are unidentified and profitably extractable.

Reserves refer to mineral or fossil fuel deposits that have been identified and can be extracted profitably using current technology and market conditions. Therefore, option B - "They are identified and profitably extractable" - best describes reserves. Options A and C both mention that the deposits are subeconomic, meaning that they cannot be extracted at a profit, while option D suggests that the deposits are unidentified, meaning that their existence has not yet been confirmed.