Visualize the kite as a triangle, with the point where the kite is anchored being 'A', the kite being 'B', and the point directly below the kite being 'C'. We know that line segment BC is 19 meters, and can use trigonometry to find the length of the string, line segment AB. The operator 'sin' can be calculated by dividing the opposite leg over the hypotenuse, so given the angle 'A', we can solve for the hypotenuse. 
. If we solve for 'x', we get 
. Plug 19 over sin(33) into your calculator and you get 34.885, so the answer is A, 35 feet
