Farmers in the deccan plateau depend mostly on which of the following factors to farm?
a. river deltas
b. irrigation
c. summer monsoons
d. runoff water from nearby mountains

The answer is Summer Monsoons.

Explanation:

Farmers in the Deccan Plateau depend mostly on B) IRRIGATION to farm.

Irrigation in the Deccan Plateau is needed because its climate is very dry. 

Deccan Plateau has a very rich farmlands. This is because of the lava flow to produces rich, black soil.

Deccan Plateau is found between the Bay of Bengal and Arabian Sea. It is a diamond shaped area bordered by Eastern and Western mountains or Ghats. People in this area farm cotton and peanuts.

.the answer is in fact C. summer monsoons.

To the south are the HIMALAYAs, Karakourum, and Kunkun, the highest mountain ranges in the world. Another barrier between west and east is the PAMIR KNOT, several mountain ranges. including the TIAN SHAN and Pamir.