Bets on rising U.S. oil prices have hit a nine-month low, underscoring investors’ concerns that a slowing economy will dent demand for crude at a time when the world is awash in oil. The number of contracts wagering on an increase in U.S. crude prices outnumbered bearish ones by 86,530 during the week ended Oct. 15, according to the U.S. Commodity Futures Trading Commission. That puts net bullish bets at their lowest level since the week ended Jan. 8. …