Answer : The carbon skeleton represents an ether is
![C-C-C-O-C-C-C](https://img.qammunity.org/2020/formulas/chemistry/middle-school/d2sqvqwmhc9ssybcetz2hwnra4s366brtz.png)
Explanation :
Ketone : It is a functional group in which the the
group is directly attached to the two alkyl group of carbon.
The general formula of ketone is,
![R-CO-R'](https://img.qammunity.org/2020/formulas/chemistry/middle-school/3a1vm69i9y5vusqte3jojggbl6j6gfn23u.png)
Ether : It is a functional group in which the the
group is directly attached to the two alkyl group of carbon.
The general formula of ether is,
![R-O-R'](https://img.qammunity.org/2020/formulas/chemistry/middle-school/25mo1g9afrejfon7oonieoyyqyzyo3tgo1.png)
Aldehyde : It is a functional group in which the the
group is directly attached to the terminal alkyl group of carbon.
The general formula of aldehyde is,
![R-CO](https://img.qammunity.org/2020/formulas/chemistry/middle-school/wm0y4k67f2hj00uzh9uelp8f564w6hzesa.png)
In the given image,
Image 1 carbon skeleton represents a ketone.
Image 2 carbon skeleton represents an ether.
Image 3 carbon skeleton represents an aldehyde.
Hnece, the carbon skeleton represents an ether is
![C-C-C-O-C-C-C](https://img.qammunity.org/2020/formulas/chemistry/middle-school/d2sqvqwmhc9ssybcetz2hwnra4s366brtz.png)