I think it’s propaganda because you can see propaganda as like an advertisement and by putting Hitler’s face as the Nazi stamp the group is relaying the message and spreading the word about Nazism.
A cult of personality is "a leader's tactic for getting unquestioned praise and worship from others through control of mass media and propaganda." <em>(Source: Flocabulary.com)</em>
Seeing as this is the actual definition of a cult of personality, a Nazi stamp with Hitler's face on it is an example of a <u>tactic for gaining praise and worship</u> so the answer is A.