$\sqrt[4]{\sqrt[3]{3^2}}$ can be expressed as :

1. $3^6$

2. $6^{1/3}$

3. $3^{1/12}$

4. $3^{1/6}$

$1.\overline{9} - 1.9$ is equal to :

1. 0

2. 1

3. 0.09

4. 0.1

When written in decimal form, which of the following will be a non-terminating and non-repeating number?

1. $1^{1/9}$

2. $2^{1/9}$

3. $2^{-9}$

4. $9^{1/2}$

Observe the values of a, b, c given in the table. If we choose numbers a, b and c from rows a, b and c respectively, what is the maximum possible value of $\dfrac{c - b}{a}$?