U.S. consumer prices recorded their biggest decline in six years in December and a gauge of underlying inflation failed to rise, which could make the Federal Reserve more cautious about raising interest rates, Reuters reported.  Other data on Friday, however, suggested that the economy was still poised for solid growth despite the soft inflation readings, with factory output rising last month and consumer sentiment hitting its highest level in 11 years in January. The Labor Department said on Friday its Consumer Price Index fell 0.4 percent last month, the largest drop since December 2008, after sliding 0.3 percent in November.