ROI and RI – how to deal with capital employed

Hi Sir
I would like to ask regarding ROI and RI calculations
For the capital employed

If it comes out in Section A or B where we can only provide one answer
And if the question is silent and did not mention as to whether the capital employed should be opening or average or closing figure

Which one should i use for the capital employed when i calculate for ROI and RI?
Thank you so much