As someone who marked that question in 2002 both answers were accepted as correct along with others e.g. changes in technology shown in the car.
With WWI questions there can be a range of responses which can get full marks and some can come from left field.
The most common response to that question was about women but some people did write about other things and do it very well.
The important thing is how well you link OWN KNOWLEDGE to the sources and how well you actually ANSWER THE QUESTION ASKED. Too many students spend all their time writing about the sources and link some own knowledge to the source without ever addressing the question itself.
Your teachers are taking the most obvious response to the question, which is not a bad thing by any means (and is what I would teach and expect my students to do) but other responses are considered on their merits.