Three masses of $15 \mathrm{~kg} .10 \mathrm{~kg}$ and $5 \mathrm{~kg}$ are suspended vertically as shown in the fig. If the string attached to the support breaks and the system falls freely, what will be the tension in the string between $10 \mathrm{~kg}$ and 5 $k g$ masses. Take $g=10 \mathrm{~ms}^{-2}$. It is assumed that the string remains tight during the motion
(a) $300 \mathrm{~N}$
(b) $250 \mathrm{~N}$
(c) $50 \mathrm{~N}$
(d) Zero