Can Null Graph be a valid Matching

Question

Definition of valid matching says that if every vertex is incident with atmost one vertex then it is a matching but I have seen coaching material note which includes null graph as a matching.I am confused please help.

Comments

yes, Null graph ( but all vertices should be present in that graph) is a Matching for any graph.

in Null graph, degree of each vertex is 0

as per Matching condition, the degree of each vertex ≤ 1 ===> Null graph satisfies