Siachen Glacier is situated to the

1. A

   East of Aksai Chin

   East of Aksai Chin. Aksai Chin is further east; Siachen is west of that tract.

2. B

   East of Leh

   East of Leh. Siachen lies north, up the Nubra/Shyok.

3. C

   North of Gilgit

   North of Gilgit. Gilgit is west, down the Indus.

4. D

   North of Nubra Valley

   North of Nubra Valley. The glacier heads the Nubra (the Siachen river).

Summary. Official key is (d). Siachen sits at the head of the Nubra Valley — north of Nubra — not east of Leh or Aksai Chin, and not north of Gilgit.