Given a Right Triangle, you need to remember the following Trigonometric Function:
In this case, you know that:
Where "O" is the opposite side and "H" is the hypotenuse of the Right Triangle.
Then, substituting values and simplifying the fraction, you get:
In order to get the value in decimal form, you need to divide the numerator by the denominator:
Hence, the answer is: Choice 'D'.