Oil prices dropped to their lowest in three months on Monday despite OPEC efforts to curb crude output, dragged down as U.S. drillers kept adding rigs. Brent crude LCOc1 had by 0011 GMT (8:11 p.m. ET) fallen 42 cents, or 0.82 percent, to its lowest since Nov. 30 at $50.95 per barrel. It closed the previous session down 1.6 percent at $51.37 a barrel. U.S. West Texas Intermediate crude (WTI) CLc1 declined 50 cents, or 1.03 percent, to $47.99 a barrel, its weakest since Nov.29. U.S. drillers added oil rigs for an eighth consecutive week, Baker Hughes said on Friday, as energy companies increased spending to take advantage of a recovery in crude prices since the Organization of the Petroleum Exporting Countries (OPEC) agreed to cut output late last year. [RIG/U] OPEC and […]