A．Those interested in the power of persuasion.  
B．Those trying to improve their public images.    
C．Those planning to take up some public work.
D．Those eager to become effective speakers.

A．Strategies different animals use to survive.   
B．Methods beavers use to gather building materials.   
C．Decisions beavers make about where to live. 
D．Choices beavers face when looking for food.

A．Aspen trees are easier to transport.  
B．Aspen trees provide better wood for construction.           
C．Aspen trees provide less nutrition for beavers. 
D．Aspen trees have more overall value to beavers.