Stability of alkenes

The following question was asked on myPAT website:



> 
> [![enter image description here](https://i.stack.imgur.com/LULj9.png)](https://i.stack.imgur.com/LULj9.png)
> [![enter image description here](https://i.stack.imgur.com/KwnU9.png)](https://i.stack.imgur.com/KwnU9.png)
> 
> 
> 




---


I started with the solution by counting the **hyper-conjugative** structures available to each alkene. Based on this concept *only*, order is:


I > II = III > IV


Then, I noticed that II and III have different **carbon count**. As, n-hexane (~68 °C) have more thermodynamic stability than n-pentane (~36 °C), therefore the order becomes:


I > II > III > IV


But, option B was incorrect. What I am doing wrong?




---


The correct option is:



> 
>  [![enter image description here](https://i.stack.imgur.com/fhogE.png)](https://i.stack.imgur.com/fhogE.png)
> 
> 
> 


