In case of auto transformer, which of the following statements are correct?

I. An auto-transformer requires less copper as compared to a conventional 2-winding transformer of the same capacity

II. An auto-transformer provides isolation between the primary and secondary windings

III. An auto-transformer has less leakage reactance as compared to the conventional 2-winding transformer of same capacity

Select the correct answer using the codes given below

A)     1,2 and 3

B)      1 and 2

C)      1 and 3

D)     2 and 3