$27^{-2/3}$\n○ 9\n○ -1/9\n○ 1/9

Explanation:

Step1: Rewrite negative exponent

$27^{-2/3} = \frac{1}{27^{2/3}}$

Step2: Rewrite as root and power

$\frac{1}{(27^{1/3})^2}$

Step3: Calculate cube root of 27

$27^{1/3} = 3$, so $\frac{1}{3^2}$

Step4: Compute the square

$\frac{1}{9}$

Answer:

1/9