(2) is the cumulative rate of return. It is the final period's end of period value divided by the initial period's start of period value:
100% ( final / initial - 1 )
(3) is the arithmetic mean of the total return, which is very non-standard:
cumulative rate of return / number of time periods
(1) is the arithmetic mean of the period profit percentages which is a simple average:
SUM( periodic profit percentage ) / number of periods
NOTE: For such low rates, the geometric and arithmetic means will be almost identical, as discovered by Irving Fisher.