A spring, whose unstretched length is l , has a force constant k . The spring is cut into two pieces of unstretched lengths ll and l2 , where, l1 = nl2 and n is an integer. The ratio k1/k2 of the corresponding force constants k 1 and k 2 will be
A .n²
B. 1/n²
C. n
D. 1/n
