i know the answer is 2, but what would the mechanism be?

14-7 What is the major product of the following reaction? CH3CH2CHCHCH Mg, diethyl ether (1) HC-0 (2) H30* 1) 2-ethyl-1-pentanol 2)2-ethyl-1-butanol 3) 3-pentanol 4) 3-methyl-1-pentanol 1) 2-ethyl-l-pentanol 2-ethyl-1-butanol Br