Susquehanna released a note to clients advising to buy Walgreen (NYSE:WAG) April $33 calls as the stock may rise in the wake of an FTC announcement on Express Scripts (NASDAQ:ESRX) and Medco (NYSE:MHS) merger.A Susquehanna derivative strategist Christopher Jacabson said there was a high probability of near-term volatility.Shares of Walgreens rose 2.1% to $33.48 on March 9th.