Answer: D. 4.5 square units
To find the area of a triangle with vertices (x1, y1), (x2, y2), and (x3, y3), we use the formula:
Area = 1/2 * |x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)|
Given vertices are (1, 2), (4, 2), and (3, 5).
Let (x1, y1) = (1, 2)
Let (x2, y2) = (4, 2)
Let (x3, y3) = (3, 5)
Area = 1/2 * |1(2 - 5) + 4(5 - 2) + 3(2 - 2)|
Area = 1/2 * |1(-3) + 4(3) + 3(0)|
Area = 1/2 * |-3 + 12 + 0|
Area = 1/2 * |9|
Area = 4.5 square units.