The area of ΔABC is 63 sq. units. Two parallel lines DE, FG, are drawn such that they divide the line segments AB and AC into three equal parts. What is the area of the quadrilateral DEGF? A. 28 sq. units B. 35 sq. units C. 21 sq. units D. 48 sq. units

DE and FG are parallel to BC and cut AB and AC at one-third and two-thirds of their length. Similar triangles have areas in the ratio of the squares of their sides: area of ADE = (1/3)² × 63 = 7 and area of AFG = (2/3)² × 63 = 28. The quadrilateral DEGF lies between them: 28 − 7 = 21 sq. units.