For the given 5 values, 15, 18, 21, 27, 39; the three year moving averages are:

18, 22, 29

The correct answer is Option (2) → 18, 22, 29

Three–year moving averages

Given values: 15, 18, 21, 27, 39

$\text{1st MA}=\frac{15+18+21}{3}=\frac{54}{3}=18$

$\text{2nd MA}=\frac{18+21+27}{3}=\frac{66}{3}=22$

$\text{3rd MA}=\frac{21+27+39}{3}=\frac{87}{3}=29$

The three-year moving averages are: $18,\;22,\;29$