ACCA Study Hub question ROCE and Payback

while calculating ROCE and Payback do we consider “Market research of $8,000 has already been carried out and has been capitalised.” or it’s considered as sunk cost

“A project being considered would require a machine costing $80,000. Market research of $8,000 has already been carried out and has been capitalised. The result is that the project is expected to last for six years and produce net cash inflows of $20,000 for each of the first three years, and then $15,000 for each of the last three years. At the end of the project, the machine will be scrapped for $4,000.

Assume that cash flows arise evenly during the year.

Required:

Evaluate the project using:

(i) ROCE;

(ii) ROCE using the average investment approach;

(iii) Payback period.”

Per ACCA they have included the market research