U.S. economic growth braked sharply in the fourth quarter as businesses stepped up efforts to reduce an inventory glut and a strong dollar and tepid global demand weighed on exports. Gross domestic product increased at a 0.7 percent annual rate, the Commerce Department said on Friday in a report that showed a further cutback in investment by energy firms grappling with lower oil prices. Growth in consumer spending also slowed as unseasonably mild weather cut into spending on utilities.