Oil investors are taking no chances that Iran’s nuclear deal with Western powers will remain intact next month. FILE PHOTO: A worker checks the valve of an oil pipe at Al-Sheiba oil refinery in the southern Iraq city of Basra, Iraq, April 17, 2016. REUTERS/Essam Al-Sudani/File Photo Volatility, a measure of options demand, for options that allow the holder to buy Brent futures between $75 and $80 a barrel, has risen this week above 30 percent to its highest since late 2016. Iran pumped nearly 4 percent of world crude oil in March, according to the International Energy Agency. The options market shows that in the last month, investors have bought more than twice as many calls at $75, $80 and $85 that expire in late May than any other option maturing at that time. Open interest in $75, $80 and $85 May calls has risen […]