Oil extends first-quarter gains on tight supply, economic optimism

LONDON (Reuters) - Oil rose on Monday, building on its largest first-quarter gains in nearly a decade, as tight supply and positive signs for the global economy supported prices.Brent crude for June delivery was up 96 cents, or 1.42 percent, at $68.54 a barrel by 0900 GMT, having risen 27 percent in the January-March period.U.S. West Texas Intermediate futures rose 56 cents, or 0.93 percent, to $60.70 a barrel, after gaining 32 percent in the first quarter. Positive Chinese factory gauges and..