question: Hint: Please answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: As shown in the figure, in the ⊙O with a radius of 2.0, C is a point on the extended line of the diameter AB, CD is tangent to the circle at point D. Connect AD, given that ∠DAC = 30.0, the length of the line segment CD is ()
  Choices:
  (A) 1
  (B) √{3}
  (C) 2
  (D) 2√{3}