You're misreading the answers. In sample A, 45% are in favor of reintroducing National Service and (38% oppose it). In sample B, the phrasing is reversed, meaning that 34% are in favor (and 48% oppose it). So, the difference is 11 percentage points.
No, you're misreading too - see my other comment.
But in that case you need to add a control for both questions without the prior four questions. How do you know the difference in phrasing doesn't matter?