Does E1cB take place over here?

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


I formed this product (reason: alkene has 6 alpha hydrogens)


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


However, it turns out, this is the answer:


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


The reason why I suspect this is e1cb is because NO2 could stabilize the carboanion (conjugate base) formed after reaction with NaOCH3


I would also like to know if a substrate has two sites for E2 elimination to occur, how do I decide site which would be preferred. Is it the one with the most acidic hydrogen or the one which would lead to a more stable alkene?


