Answer: second option.
Explanation:
Find the distance AE by subtracting AB and DC and dividing by 2:

Knowing the length of DE and AE, you can apply the Pythagorean Theorem to calculate the distance AD, which would be the hypotenuse of the triangle ADE:

Where "a" is the hypotenuse and "b" and "c" are the legs of the triangle.
Then:

Substituting values into
you get that the lenght of AD is:
