A brick having a mass of 4.0 kg is dropped from a height of 2.0 m...

Total height fallen by the brick is $h = 2.0 + 1.0 = 3.0 \text{ m}$

Loss in gravitational potential energy is $\Delta U = mgh$

Taking $g = 10 \text{ m/s}^2$, we get $\Delta U = 4.0 \times 10 \times 3.0 = 120 \text{ J}$

Thermal energy produced is $80\%$ of the loss in potential energy

$E = 0.80 \times 120 = 96 \text{ J}$

Converting joules to calories using $1 \text{ cal} \approx 4.2 \text{ J}$

$E = \dfrac{96}{4.2} \approx 22.85 \text{ cal}$

The closest value among the options is $23 \text{ cal}$