Sam recently moved to a new city and has had to learn many new telephone numbers. Now he has difficulty remembering the numbers of his old friends in his former location. Forgetting is most likely due to

encoding failure

Explanation:

As in the question it is mentioned that Sam moved to a new city due to which he feels difficult to remember his old friend number. Now according to the tulving encoding principle, the retrieval would be successful the cue must be similar at the time of encoding

hello,

answer: a federal government has final authority on interstate/inter provincial  and international affairs, a confederation is one where the central/national government or authority is governing body what does not have final say over the same matters. hopefully this and i will try again if you don't like this answer : )

best of luck!