The answer is: 
[B]: 
 * 16 .
_______________________________________________The formula for the "circumference" of a circle is: 

 * diameter.
___________________________________________________ C = 

 * d ;
___________________________________________________ We are given: d = 16 ft. ;
___________________________________________________So, C = 

 * 16 ft. ;
___________________________________________________
 And answer choice: [B]: " 
 * 16 " ; is the closest expression among the answer choices given.____________________________________________________