Silver atom has completely filled d orbitals (4d) in its ground state. How can you say that it is a transition element?
Ag has a completely filled 4d orbital (4d5s) in its ground state. Now, silver displays two oxidation states (+1 and +2). In the +1 oxidation state, an electron is removed from the s-orboital. However, in the +2 oxidation state, an electron is removed from the d-orbital. Thus, the d-orbital now becomes incomplete (4d). Hence, it is a transition element.