HOUSTON, Jan. 29, 2013 /PRNewswire/ -- Merger and acquisition (M&A) activity in the U.S. oil and gas industry hit a ten-year high during the fourth quarter of 2012 with 75 deals, according to PwC US. A number of factors drove this activity, including private equity (PE) interest, foreign buyers, shale plays, and companies looking to get deals done before the end of the year with the looming fiscal