Here's why the oil and gas company is a buy after today's price drop.Shares of ConocoPhillips (COP -3.94%) tumbled this morning and were trading 3.5% lower as of 11:30 a.m. ET on Wednesday.With several of its peers on a buying spree in recent months, today's big announcement from ConocoPhillips shouldn't have surprised investors. The oil and gas company is acquiring a peer in a multibillion-dollar deal and expects the acquisition to create long-term value for shareholders.ConocoPhillips will acquire Maratho ...