The ratio of the areas is
[tex]16\textrm{ cm} \times 8 \textrm{ cm} : 72 \textrm{ sq m}[/tex]
[tex] 16 \times 8 \textrm{ cm}^2 : 9 \times 8 \textrm{ m}^2[/tex]
[tex] 16 \textrm{ cm}^2 : 9\textrm{ m}^2[/tex]
The scale is the ratio of the lengths, which is the square root:
[tex]4 \textrm{ cm} : 3 \textrm{ m}[/tex]
First choice
