Elimination vs reduction reactions - how to tell

Here are two compounds:


Compound H:


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


and compound I:


[![enter image description here](https://i.stack.imgur.com/m5tbq.png)](https://i.stack.imgur.com/m5tbq.png)


Compound H reactions with the reagent shown below to form compound I and two other products.


How would you clarify this reaction? I thought it was a reduction, because we are losing the oxygen bonded on the left hand side of the molecule. The actual answer is **elimination** Any advice for tell-tale signs for this type of reaction, and why my answer was wrong?


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


