What recourse does B have if they discover an easement across the land after acquiring it?

If B discovers an easement across their land after acquiring it, the most appropriate recourse is to pursue warranty claims against the seller, S. This is because when B purchased the property, there may have been an implied or explicit warranty in the sales contract that the property has a clear title and is free from undisclosed encumbrances, such as easements. If S failed to disclose the existence of the easement prior to the sale, B may have grounds to claim that they were misled, which could allow them to seek damages or other remedies under the warranty provisions of the sale.

In real estate transactions, the inclusion of warranties is common to protect the buyer from undisclosed issues with the property. Therefore, this option provides B with a legitimate course of action to address the situation legally, seeking restitution or compensation for any issues arising from the undisclosed easement.