$13.$ Using non$-$circular wire for helical springs can:

A$)$ Make the springs invisible

B$)$ Increase the flexibility of design in achieving desired spring characteristics

C$)$ Decrease the electrical resistance of the spring

D$)$ Change the color of the spring under load

$14.$ The primary advantage of using helical springs made from non$-$circular wire is:

A$)$ Improved aesthetic appeal

B$)$ Enhanced strength and durability for a given weight

C$)$ Reduced manufacturing time

D$)$ Increased electrical conductivity