What is the primary obligation of the grantor under a covenant of further or future assurances?

The primary obligation of the grantor under a covenant of further or future assurances is to produce any documents needed to perfect the title. This covenant is a promise made by the grantor that they will take necessary actions or provide additional documentation in the future if required, to ensure that the grantee has a complete and legal title to the property. This could involve providing additional deeds, correcting any defects in the title, or ensuring that the grantee's ownership is undisputed.

The other choices relate to different responsibilities that may not specifically fall under this covenant. For instance, maintaining the property, ensuring it is free of zoning disputes, or paying property taxes are not directly related to the specific obligation of perfecting the title. Thus, the focus here is primarily on the grantor's duty to assist the grantee in establishing or securing their rightful ownership of the property, which is encapsulated in the chosen answer.