The Running Yard for a Dog Kennel Must Contain at Least

Multiple Choice

The running yard for a dog kennel must contain at least 400 square feet. If a 15-foot side of the kennel is used as part of one side of a rectangular yard with 400 square feet, what dimensions will require the least amount of fencing? Round your answer to the nearest feet. ​​

A) 40 ft by 10 ft
B) 400 ft by 1 ft
C) 20 ft by 20 ft
D) 40 ft by 5 ft
E) 80 ft by 5 ft