In the direct variation equation of the form \( y = kx \), the constant of proportionality \( k \) is the coefficient of \( x \).
In your equation, \( y = 2 \frac{2}{3} x \), we can convert \( 2 \frac{2}{3} \) into an improper fraction:
\[ 2 \frac{2}{3} = \frac{8}{3} \]
Thus, the equation can be rewritten as:
\[ y = \frac{8}{3} x \]
Therefore, the constant of proportionality \( k \) is \(\frac{8}{3}\).
Since this option isn't listed among your responses, the most fitting option in your context is 2 and 2 thirds (which is the same as \( 2 \frac{2}{3} \)).