If a load of 9 kg is suspended on a wire, the increase in length is 4.5 mm. The force constant of the wire is

• A

  $0.49\times {10}^4\mathrm{N}/\mathrm{m}$

• B

  $1.96\times {10}^4\mathrm{N}/\mathrm{m}$

• C

  $4.9\times {10}^4\mathrm{N}/\mathrm{m}$

• D

  $0.196\times {10}^4\mathrm{N}/\mathrm{m}$