1. Given data

   • Mass of bullet: $m = 50\text{ g} = 0.05\text{ kg}$
   • Initial speed: $u = 100\text{ m/s}$
   • Final speed: $v = 40\text{ m/s}$

2. Initial kinetic energy $K_i = \frac{1}{2}mu^2$ $K_i = \frac{1}{2}(0.05)(100)^2$ $K_i = 0.025 \times 10000 = 250\text{ J}$

3. Final kinetic energy $K_f = \frac{1}{2}mv^2$ $K_f = \frac{1}{2}(0.05)(40)^2$ $K_f = 0.025 \times 1600 = 40\text{ J}$

4. Loss in kinetic energy $\Delta K = K_i - K_f = 250 - 40 = 210\text{ J}$

5. Percentage loss of kinetic energy $\%\text{ loss} = \frac{\Delta K}{K_i} \times 100$ $\%\text{ loss} = \frac{210}{250} \times 100 = 84\%$

6. Option check

   • A: $44\%$ ❌
   • B: $16\%$ ❌
   • C: $84\%$ ✅
   • D: $32\%$ ❌

Therefore, the correct answer is Option C.