Depsang and Rupsa are:

Correct answers: (a) High plateaus or (d) High plains

Explanation

Depsang and Rupsa (Rupshu) are high-altitude, almost flat surfaces of Ladakh:

• the Depsang Plains in the north, near the Karakoram Pass and the Line of Actual Control, a gravelly plain at about 5,300 m;
• Rupshu in the south-east, a high, flat region of brackish lakes such as Tso Moriri, at about 4,500 m.

They are commonly called the high plains of Ladakh.

The book's key is (d), high plains. Rupshu is also described as a high plateau, so (a) is also accepted.