Maya decides to use the method of proportions and similar triangles to find the height of a tower. She measures the length of the tower's shadow and finds it is 20 feet long. Then she holds a 12-inch ruler perpendicular to the ground and finds that it casts a 4-inch shadow. How tall is the tower? a. 2.4 ft c. 60 ft b. 5 ft d. 240 ft