Generics - Programming

Q1:

Which one of the following classes are present System.Collections.Generic namespace?
  1. Stack
  2. Tree
  3. SortedDictionary
  4. SortedArray

A 1 and 2 only

B 2 and 4 only

C 1 and 3 only

D All of the above

E None of the above

ANS:C - 1 and 3 only

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