What is true when Owner A needs an easement from Owner B to access the highway and Owner B agrees?

The correct choice is that Owner B grants the easement. In situations where one property owner needs access to a public road or highway across another property, it is typically the responsibility of the property owner granting the right of access to create the easement. This involves Owner B providing permission for Owner A to use a specified part of their property for access to the highway.

In this context, the act of granting the easement means that Owner B has agreed to allow Owner A the legal right to cross their property. The arrangement can be formalized through a written agreement that outlines the terms and conditions under which Owner A can use the easement.

The other considerations, such as purchase of the easement or the need for government approval, may not apply in all situations. Furthermore, an easement by necessity is a specific type of easement that occurs under particular conditions, usually when a property is landlocked. In this case, while Owner A needs access, it doesn't automatically imply that the easement is classified as one of necessity unless specific legal criteria are met. Therefore, it remains clear that the primary legal action in this scenario is that Owner B grants the easement to Owner A.