With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: In 1995 Mobil, an American oil company, discovered oil in Equatorial Guinea. The country subsequently experienced rapid economic development; earnings from the country's oil wealth have reached the population and the country ranks high on the UN human development index. Some 20% of children die before age 5 and more than 50% of the population lacks access to clean drinking water. President Teodoro Obiang is widely suspected of using the country's oil wealth to enrich himself and his associates. In 2006, Forbes estimated his personal wealth at $600 million.
text_B: Did the discovery of oil in Equatorial Guinea contribute significantly to the country's economic development?
YES.