A spring of spring constant $5 \times 10^3 N/m$ is stretched initially by 5 cm from the unstreched position. Then the work required to stretch it further by another 5 cm is

Question

( A ) 12.5 N-m
( B ) 18.75 N-m
( C ) 6.25 N-m
( D ) 25.00 N-m