Correct structure of $$\gamma$$-methylcyclohexane carbaldehyde is

Explanation: The parent structure is $$\mathrm{cyclohexane\ carbaldehyde}$$, which consists of a cyclohexane ring attached directly to an aldehyde group $$\mathrm{(-CHO)}$$.

In common nomenclature, the ring carbons are designated using Greek letters relative to the carbon attached to the aldehyde group:

$$\mathrm{\alpha}$$ carbon: directly attached to $$\mathrm{-CHO}$$

$$\mathrm{\beta}$$ carbon: adjacent carbon

$$\mathrm{\gamma}$$ carbon: third carbon from the functional group

$$\mathrm{\delta}$$ carbon: fourth carbon from the functional group

The prefix $$\mathrm{\gamma\text{-}methyl}$$ indicates that a methyl group $$\mathrm{(-CH_3)}$$ is attached to the $$\mathrm{\gamma}$$ carbon.

Thus, the structure corresponds to a methyl substituent at the third position relative to the aldehyde-bearing carbon.

Hence, the correct structure is:

$$\mathrm{3\text{-}methylcyclohexanecarbaldehyde}$$

which is equivalent to:

$$\mathrm{\gamma\text{-}methylcyclohexane\ carbaldehyde}$$. Thus, A is the right option.