In Fig. 14.46, the area of ΔABC (in square units) is

The coordinates of A are (1, 3).

∴ Distance of A from the x-axis, AD = y-coordinate of A = 3 units

The number of units between B and C on the x-axis are 5.

∴ BC = 5 units

Now,

Area of $\triangle \mathrm{ABC}=\frac{1}{2} \times \mathrm{BC} \times \mathrm{AD}=\frac{1}{2} \times 5 \times 3=\frac{15}{2}=7.5$ square units

Thus, the area of ∆ABC is 7.5 square units.

Hence, the correct answer is option C.