Question

The opportunity cost of? tesla's investment in a new battery factory in nevada is

Answer 1

The opportunity cost of Tesla's investment in a new battery factory is WHAT THE COMPANY CONSIDERED TO BE THE BEST FORGONE OPTION TO THE FACTORY.
In economics, opportunity cost refers to the alternative which have to be given up in order to enjoy another alternative or choice. 

Answer 2

I believe the answer is: what the company considered to be the best foregone option to the factory.

Opportunity cost refers to the option that we have to sacrifice when we are choosing the other option. In a factory, the opportunity cost would be the type of materials, production strategy, or products that must be abandoned because there are others that are more efficient and profitable