For the given five values 12, 15, 18, 24, 36; the three-year moving averages are:

15, 19, 26

The correct answer is Option (3) → 15, 19, 26

$\text{Given data } : 12,15,18,24,36.$

$\text{First 3-year average } = \frac{12+15+18}{3} = 15.$

$\text{Second 3-year average } = \frac{15+18+24}{3} = 19.$

$\text{Third 3-year average } = \frac{18+24+36}{3} = 26.$

$\text{Three-year moving averages are } 15,19,26.$