TWO opposite faces are painted green and the remaining faces are painted red.Only two faces are coloured green and four are coloured red.Only 8 EDGES are there that adjacent faces are red and green coloured.Corners on those edges not included because they have 2 red and one green-colored FACE.So, Cubes which have one red and one green face = 8 × 2 = 16Hence, "16" is the correct ANSWER.