In the list, some factors increase ground roll, some decrease it, with the caveat that the effect of flap is not simple - depends on how much and when you select it - and that density and pressure altitude are linked

Nevertheless I got the required answer by selecting 1, 3, 5, and 8, all of which the examiner assumes give a shorter roll. The rest of the choices give some up and some down, so no clear cut answer

Bad question The examiner is trying to be too clever...