sample or population correct, please, standard, investment

busprof

in 5 year period the annual return on an investment are 5%,-3%,-4%,2% and 6% the standard deviation on this investment closest to

A.4.0%
B.4.5%
C.20.7%

If i consider it is sample --> Sd (sample) =4.5%
If i consider it is population -->Sd(population)=4%


Which one is correct answer

I think in 5 year period of annual return is population

could you please clarify it for me