Explanation:

1. Common Noun:
A common noun is a generic name given to a person, place, thing, or idea. It does not refer to any specific individual or entity. For example, words like teacher, city, and book are common nouns because they can refer to any teacher, any city, or any book.

2. Proper Noun:
A proper noun, on the other hand, is a specific name given to a particular person, place, or thing. It is capitalized because it refers to a unique individual or entity. For example, names like John, London, and Harry Potter are proper nouns because they refer to specific individuals or places.

Professor Martin:
In the given question, "Professor Martin" is mentioned. To determine whether it is a common noun or a proper noun, we need to consider the context in which it is used.

If "Professor Martin" is being used as a general term to refer to any professor named Martin, then it would be a common noun. However, if "Professor Martin" is referring to a specific individual named Martin who is a professor, then it would be a proper noun.

The question states that the correct answer is option 'B', which implies that "Professor Martin" is a proper noun. This suggests that "Professor Martin" is a specific individual named Martin who holds the title of professor.

Therefore, based on the given information, we can conclude that "Professor Martin" is a proper noun.