\(a,\frac{2}{\sqrt{13}-\sqrt{11}}+\frac{5}{4+\sqrt{ }11}-\sqrt{52} \)
b,\(\sqrt{6+2\sqrt{5}+\sqrt{9-4\sqrt{5}}-\sqrt{20}}\)

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

No one but the experts was able to realize that the painting was an imitation. It greatly resembled the original.

A. It was obvious that only a person with great talent could fake a painting so successfully.

B. It was almost impossible for amateurs to realize that the painting was not authentic, though the experts could judge it quite easily.

C. The painting looked so much like the authentic one that only the experts could tell it wasn’t genuine.

D. It was hard for ordinary people to judge between the fake painting and the real one.