"The green mug or the blue cup seem like a good choice" is the only sentence that uses a verb that agrees with its compound subject, since the others have issues with number.
Oxymoron : phrases that seems to be contradict each other but actually not.
Example of it are :
" O Brawling love !, O loving hate !"
" Good night ! Good Night ! parting is such a sweet sorrow"
"Beautiful Tyrant"
hope this helps