Which of the following compounds does not show tautomerism?

Which of the following statements is false regarding the enolization of

$\left(\mathrm{a}\right)$ It can form two types of enolic forms of equal stability.

$\left(\mathrm{b}\right)$ It can form two types of enolic forms of different stability.

$\left(\mathrm{c}\right)$ It can form more than two types of enolic forms of different stability.

$\left(\mathrm{d}\right)$ It can form only one type enolic form.

Keto-enol tautomerism is observed in

(a) 

(b) 

(c)    

(d)      

If ${\mathrm{D}}^{+}$ is catalyst. What is the compound $\mathrm{A}$?

What is the maximum number of geometrical isomers possible for the following compound?

Which of the following cycloalkanes will show cis-trans isomerism?

(a)   

(b)    

(c)     

(d)