The answer is false, from the Huawei online video i watched, they say it clearly, for "for point to point interface (such as serial interface), you MUST specify the OUTBOUND interface.
But sincerley from my personal understanding, given that on a point to point ineterface we only have two devices connected on either ends, so configuring the outbound interface will imply the next hop. Another administrator could just configure the next hop, instead of the outbound interface given that it is the same thing.

Meanwhile on a Broadcast multi access interface(BMA), one interface may be connected to multiple outbound interfaces, so precising the NEXT HOP is of high IMPORTANCE.

False is the correct answer; for serial interface we MUST configure the outbound interface.