For the first part of the answer look at the Vspeed tables on pages 64 and 65 of the CAP 698. The slope adjustment tables at the top of each page show how slope affects V1. These show that downslope (- slopes) require V1 to be reduced.
So options a and b are possible.
Now look at the field limit graph on page 55. If you select any given TOM and work backwards through the graph you can get the distances required. At the bottom of the graph you will see that going straight down to any value of downslope, then following the curves back to the reference line, tends to decrease the distances.
So a downslope will decrease V1, and decrease the distances required. Whether or not this was really the option you chose is of course a different question.
Remember WX Man, you thought that you would fail AGK then walked it. Stop worrying, you have probably done it again.
For those who are taking exams this month, the CAA have anounced that because of the Easter break, the results will not be released before 26 April.