The sluggish export sales were compounded this week when Egypt rejected U.S. wheat supplies because it said they were too pricey, instead purchasing grain from rival producers France and Romania. Still, analysts said Friday's drop in prices could help encourage foreign buyers to seek U.S. wheat in coming days. March wheat slid 17 1/2 cents, or 3.3%, to $5.10 ¼ .Corn and soybean futures also fell, weighed down by profit-taking and options expiration, with prices falling on the last trading day for March options. Corn prices also were buffeted by falling crude-oil prices, which have in recent weeks influenced grain prices, since lower oil and gasoline prices typically discouraging refineries from blending ethanol into gasoline, reducing demand for corn