Which right ensures the owner of a dominant tenement accesses another's land?

The correct answer is the easement, which is a legal right that allows the owner of a dominant tenement (the property that benefits from the easement) to access another's land (the servient tenement). This provides a specific use of the land, such as a right of way or utility access, facilitating necessary activities that would otherwise be obstructed. Easements are critical in land use and property rights, ensuring that the owner of the dominant tenement can legally utilize a portion of the servient tenement without having full ownership.

The other options do not relate to land access rights. Dower and curtesy are traditional legal rights giving a surviving spouse a life interest in a deceased spouse's property, while elective share pertains to a spouse's right to claim a portion of a deceased spouse's estate despite any testamentary dispositions. Dual agency refers to a real estate scenario where a single agent represents both the buyer and the seller in a transaction, not relating to land access rights. Thus, easements specifically address the issue of accessing another's land, confirming its role as the correct answer.