Among the following structures,which will show the most stable enamine formation?
(Where $Me$ is $-CH_{3}$)

Which of the following is more stable than the remaining three?

For the following carbocations,the correct order of stability is:
$I: ^+CH_2-COCH_3$
$II: ^+CH_2-OCH_3$
$III: ^+CH_2-CH_3$

Stability order of the following carbocations:
$(i) CH_3 - C^{+}(OCH_3) - CH_3$
$(ii) CH_3 - C^{+}(CH_3) - CH_3$
$(iii) CH_3 - NH - C^{+}H_2$
$(iv) CH_3 - C^{+}H_2$

The correct stability order of the following carbocations is:
$I$. $H_2C^+-CH=CH-CH_3$
$II$. $H_2C^+-CH=CH-BMe_2$
$III$. $H_2C^+-CH=CH-NMe_2$
$IV$. $H_2C^+-CH=CH-OMe$

In the above reaction,the left-hand side and right-hand side rings are named as '$A$' and '$B$' respectively. They undergo ring expansion. The correct statement for this process is: