In his speech, stalin refers positively to lenin and then repeats one of lenin's famous quotes. what type of audience appeal is he using? a. telos b. pathos c. ethos d. logos

Stalin is using Ethos.  In using quotes from Lenin, Stalin was building "credibility or trustworthiness."  Wanting to convince an audience, the use of Ethos shows expertise and confidence. Quoting other great works or leaders may express experience and knowledge. 

The answer to your question then is C, Ethos.

He discusses the problem of human destruction of nature and gives solution to prevent it.

Not really sure but wow ur work is hard