Brent crude oil plunged on Wednesday after details of a framework memorandum of understanding between Iran and the US, disclosed by Iranian media, fueled market optimism over the prospects of US-Iran negotiations. Although the White House quickly denied the authenticity of the document, investors continued to bet that a deal is moving closer. Soybean oil futures on the Chicago Board of Trade (CBOT) were unaffected by the sharp drop in crude oil. Constrained by domestic inventories, China's vegetable oil markets showed a relatively weaker trend.