Multi-choice problem: Choose from the options at the end, and answer how do you do this: How do I draw a 45 cm diameter circle on the leather ?

Pick from: (I). Cut a 22.5 cm string with scissors, fix one end on the string on the leather with you left hand and grab the other end of the string with your right hand while holding a pencil. By tensing up the string, draw a circle with your right hand.; (II). Cut a 22.5 cm string with scissors, fix one end on the string on the leather with you left hand and grab the other end of the string with your right knee while holding a pencil. By tensing up the string, draw a circle with your right knee.;
(I).