Options A and D: Nouns are words that name people, things, places,
animals, etc. In the given sentence, 'Carl' is a noun that names a
specific person. 'Eiffel Tower' is a name given to a specific, famous structure in Paris.
Hence these are nouns and options A and D are correct.
Options B and C: Verbs are words that express an action. 'See' is a verb in this
sentence that means 'to perceive through the eyes'.
'Wants' is a verb that means 'to wish for something'.
These words are verbs and not nouns and hence both options are wrong.