Dedicated AC line - Contractor wants to use BX instead of romex

Contractor said that mice or rats can eat through romex, which didn't concern me.    I'll have to find out what local NYC code is.

So mice eat in-wall Romex. So says the “code”. So no Romex for in-wall. Because against “code”. I honestly had no idea. I learn new things every day

If you're in a converted industrial building or similar it might be code. It might also be the contractor has run into that problem in your area. If possible it would make no difference if your special wire was run in flexible  conduit if the contractor agrees. 

Thanks for all the replies so far (except that nasty one).   In doing some research it seems BX (named for the Bronx, where it was invented) is required in buildings like mine (over 3 stories).

So any suggestions on a particular metal clad cable to use?  (Steel or aluminum?).  I know there is an oversize neutral cable but the increased diameter would be to hard to work with in my situation (requires some 90 degree bends.    I imagine someone might cryo BX?  

Why I ALWAYS choose BX over Non-Metallic (NM) cable: A real-world example.

Sometimes individual conductors run inside conduit is the only option, but when I have a choice between NM cable and BX, I always choose BX as a residential wiring best practice. There are two main reasons:

1)   BX shields electric fields. Many of my concerned clients have spent a lot of effort and money to shield against and reduce their exposure to electric fields. Some even go as far to turn off the circuits to their bedrooms when they sleep to reduce their exposure. If construction, remodels and renovations are done with BX, the electric field exposure is significantly reduced. The cost is greater, but for a 250-foot roll of BX, it is only about $30 more expensive than NM cable. So for a small job, the extra cost may only be $100 or so, and even for a large job the extra cost should not exceed $1,000.

Source: https://healthybuildingscience.com/2013/01/15/residential-wiring-best/#:~:text=2)%20BX%3A%20BX%20is%....