Identify the types of nouns present in the following sentence:
Tokyo is the most popular city in the world.
A. Tokyo – Proper noun; city, world – Common nouns
B. Tokyo – Common noun; city, world – Proper nouns
C. Toyo, city – Proper nouns; world – Common noun
D. Tokyo, City – Common nouns; world – Proper noun

Hint: Proper nouns are the things, places or people that have a specific name for themselves.
Common nouns are general names of things, places or people, which are usually not unique – sometimes there are many like them.

Complete step by step answer:
Option A – The word Tokyo is the specific name of a city that is located in Japan, which makes it a proper noun. The words city and world are rightly indicated as common nouns because they do not have a specific name. This is the right option.
Option B – Tokyo is a specific name and is not a common noun. City and world, on the other hand are not specific names and hence are not proper nouns. This is not the right option.
Option C – Tokyo qualifies to be a proper noun but not the word city. The word world is rightly indicated as a common noun; but the whole answer is not up to the mark hence this is not the right option.
Option D – The word city is a common noun but not Tokyo. World cannot be a proper noun because it does not have a specific name to it. This is not the right option.

Thus, the correct option is (A)

Note:
Proper nouns are names and common nouns are things, places and people without any names.