Definition of matching :- Given a graph , a matching M in G is a set of pairwise set of non adjacent edges , that is no two edges shares common vertices .
Definition of maximal matching :- A maximal matching is a matching of a graph G, that is not a subset of any other matching .
Clearly see they have asked noof maximal matchings not the maximum matching.
From the above graph ,
Assume edges are e1,e2,e3,e4,e5( consecutive edges) .
The maximal matchings possible are
{ e1,e3,e5} , { e2,e4} , {e1,e4} , {e2,e5} .
So , noof maximal matchings are 4 .
If they have asked about maximum matching size then it is 3 as {e1,e3,e5} is maximum matching possible