Which of the compound will show tautomerism?
Correct option is D. All of these
$$\bf{Hint-}$$ Tautomerism is a phenomenon where a single chemical compound tends to exist in two or more interconvertible structures that are different in terms of the relative position of one atomic nucleus which is generally the hydrogen.
$$\bf{Correct\ option-}$$ $$D$$
$$\bf{Explanation\ for\ correct\ options-}$$
Conditions to show tautomerism:
1. Compounds should be planar.
2. It should have $$sp^3$$ hybridized carbon which has at least one $$\alpha$$ hydrogen.
In options $$A$$, there is $$sp^3$$ hybridized carbon with $$\alpha-$$ hydrogen. So this compound will show tautomerism.
In options $$B$$, there is $$sp^3$$ hybridized carbon with $$\alpha-$$ hydrogen. So this compound will show tautomerism.
In options $$C$$, there is $$sp^3$$ hybridized carbon with $$\alpha-$$ hydrogen. So this compound will show tautomerism.