Answer: The right answer is the D) It compares oranges to "golden mountains" to contrast wasted abundance and hungry people.
Explanation: Just to elaborate a little on the answer, it can be added that here Steinbeck is denouncing the atrocity that took place during the Great Depression, where food was literally and purposedly wasted and destroyed rather than given, for free, to the people that needed it desperately. The fields were filled with oranges, to the extent that they looked golden, yet the oranges were sprayed with kerosene so the hungry people could not take them without paying for them.