De facto,
If you offered your answer in the current EASA ATPL exams you would be marked incorrect.
The examiner currently is of the opinion that a downslope reduces TODR and ASDR as the effect of increased acceleration and therefore earlier V1 out ways the increased deceleration distance.
With the caveat that this is not true for VMBE limited take-offs.
The reality is that for each type it will be different and for any one type the effect of slope will be tempered by other variables.