The answer is (c) Improvements: Permanent additions to land are called improvements.
Explanation for each option:
(a) Encumbrances: These are claims, liens, or liabilities attached to real property that may diminish its value or restrict its use, but they are not physical additions to the land.
(b) Chattel: This term refers to personal property that is movable, as opposed to real property, which is immovable. Chattel is not related to permanent additions to land.
(c) Improvements: This term refers to permanent additions or changes made to land or buildings that enhance the property's value or utility. Examples include buildings, roads, and other structures.
(d) Encroachment: This occurs when a structure or improvement extends beyond the boundaries of a property onto neighboring land, but it is not a term for permanent additions to land itself.
In summary, improvements are the correct term for permanent additions to land.