[单选题]
A 10-kg mass, hung onto :b-4bp,,sjcv:p whgy2 g a3pfa u88xuy55+e l;uqraq az-p v cryeqe1q9-qa); spring, causes the spring to stretch 2.0 cm. What is the spring constanteauqq+l5;aa)p -urqc xz1qurye8 v ;q-9e8y5?
A. $4.9 \times 10^{3} \; N/m$
B. $5.0 \times 10^{3} \; N/m$
C. 20 N/m
D. 2.0 N/m
