Answer :
None
In that sentence there are no proper nouns proper nouns are places, names, etc.
There are no proper nouns in that sentence a proper noun is places,names,etc.
In that sentence there are no proper nouns proper nouns are places, names, etc.
There are no proper nouns in that sentence a proper noun is places,names,etc.
Well,
There are none if none of the words in the original question begin with a capital letter.
There are none if none of the words in the original question begin with a capital letter.