a

Here we can see two triangles:

i) ΔABC, ii) ΔADC

Now lets find out the area of triangles:

i) Area of ΔABC = \(\frac{1}{2}\) × Base(AC) × Height 

                           =  \(\frac{1}{2}\) × 4 × 1 = 2 cm²

ii) Area of ΔADC = \(\frac{1}{2}\) × Base(AC) × Height 

                           =  \(\frac{1}{2}\) × 4 × 2 = 4 cm²

Area of Quadrilateral = area of ΔABC + area of ΔADC = 2 + 4 = 6 cm²