You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
1973_oil_crisis

Context:
On August 15, 1971, the United States unilaterally pulled out of the Bretton Woods Accord. The US abandoned the Gold Exchange Standard whereby the value of the dollar had been pegged to the price of gold and all other currencies were pegged to the dollar, whose value was left to "float" (rise and fall according to market demand). Shortly thereafter, Britain followed, floating the pound sterling. The other industrialized nations followed suit with their respective currencies. Anticipating that currency values would fluctuate unpredictably for a time, the industrialized nations increased their reserves (by expanding their money supplies) in amounts far greater than before. The result was a depreciation of the dollar and other industrialized nations' currencies. Because oil was priced in dollars, oil producers' real income decreased. In September 1971, OPEC issued a joint communiqué stating that, from then on, they would price oil in terms of a fixed amount of gold.

Question:
Why did oil start getting priced in terms of gold?

oil was priced in dollars, oil producers' real income decreased