I am guessing that you were tempted by answer choice E because lines 46-49 reads: "This redistribution increases the rotational acceleration of the mantle, causing friction and turbulence near the outer core-mantle boundary and initiating a reversal of the magnetic field." So it is true that friction between the outer core and mantle brings about the reversal. However, answer choice E says that friction between outer core and inner core brings about the reversal (not between the outer core and mantle). So it is a one word difference (easy to miss, but extremely important).
I hope that helps. Feel free to follow-up if that was not what was leading you towards Answer choice E.
