When using the given diagram, the following steps prove the Pythagorean theorem. Step 1: Given yellow triangle abc Step 2: Construct 3 triangles congruent to yellow triangle abc. Step 3: (a + b)2 = c2 + 4( 1 2 ab) Step 4: a2 + 2ab + b2 = c2 + 2ab Step 5: a2 + b2 = c2 Which expression in the proof represents the area of each triangle? A) 4( 1 2 ab) B) 1 2 ab C) ab D) 2ab