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'.