Question

Rewrite the given sentence, if necessary:
Mumbai that is an important port is also the largest city of India.

• A. No change
• B. Mumbai, that is an important port, is also the largest city of India.
• C. Mumbai, which is an important port, is also the largest city of India.
• D. Mumbai is the largest city of India

Answer 1

The correct option is C Mumbai, which is an important port, is also the largest city of India.

An adjective clause is a group of words that contain a subject and a verb, and it functions as an adjective that modifies a noun or a pronoun. Adjective clauses usually begin with relative pronouns such as who, whom, whose or a relative adverb like when, where and so on.
A defining adjective clause gives essential information about the noun/pronoun that it modifies, without which the meaning of the sentence is incomplete.
A non-defining adjective clause merely gives extra information about the noun/pronoun which isn't important to the sentence. Hence that clause is separated, using commas, from the rest of the sentence.
The adjective clause "which is an important port" is extra information. It isn't essential in identifying the noun, Mumbai. Hence it's a non-defining clause, which must be separated by commas and option C is correct and A is incorrect.
Option B is incorrect because 'that' is a relative pronoun usually used when the noun is one out of many; Mumbai is only one specific city, hence 'which' is preferred.
Option D is incorrect because the adjective clause is missing.