US Consumer Price Index (CPI) dropped 0.1 percent in October from the previous month on a seasonally adjusted basis due to declining energy prices, reported the Labor Department on Wednesday. Energy prices decreased 1.7 percent in October after a 0.8 percent increase in the prior month. Gasoline prices dropped 2.9 percent. Meanwhile, food prices edged up 0.1 percent in October from the previous month. Excluding the volatile food and energy categories, the so-called "core" inflation index rose 0.1 percent in October, the same increase as in September. The consumer price index has risen 1.0 percent in the 12 months ending October, the smallest 12-month increase since October 2009. Economists monitor core inflation index to get a sense of broader inflation trends, a key barometer for monetary policy decision of the central bank.