A speaker who argues, "we shouldn't be focusing on hunger in africa when children in our own country are left starving," is using which fallacy to advance his/her claim?

Red herring, specifically "Fallacy of relative privation".

A red herring fallacy is one who's intent is hide the lack of a real argument, or to replace the subject being discussed. In this case, the subject is "hunger in Africa" being replaced by "children in own country starving". The specific fallacy of relative privation is more commonly known as "not as bad as" where the introduced subject is claimed to be more severe than the original subject and therefore the original subject should be ignored until the introduced subject is resolved.