Answer:
 D) (√13)/2
Explanation:
You want to know the cosecant of the angle measured clockwise from the +x axis with point (6, 4) on its terminal side.
Cosecant
The cosecant of the angle is the ratio of the point's distance from the origin to the y-coordinate. 
The distance from the origin is found using the Pythagorean theorem:
 d = √(x²+y²) . . . . . . . distance from the origin to (x, y)
 d = √(6² +4²) = √52 = 2√13
Then the desired ratio is ...
 csc(θ) = d/y = (2√13)/4
 csc(θ) = (√13)/2