-  the latter

The error is in part 4 of the sentence. It should be "the former is greater than the latter" instead of "the former is greater than latter." Here, the article "the" is missing before "latter." Let's break down the sentence and understand the grammar rules involved:

• "Kabir and Rahim" is a compound subject because it refers to two people.
• "are" is the linking verb that connects the subject to the predicate, which is "great poets."
• "but" is a conjunction that shows contrast between the two parts of the sentence.
• "the former" and "the latter" are used to refer to two people, places, or things that have been previously mentioned in the sentence.
• "greater than" is a comparison phrase used to show that Kabir is superior to Rahim.

Now, let's look at some relevant definitions and formulas:

• A compound subject is made up of two or more simple subjects that share the same verb. For example: "The dog and the cat chase birds." Here, "the dog" and "the cat" are the simple subjects, and "chase" is the verb they share.
• A linking verb connects the subject of a sentence to a noun or adjective that describes it. For example: "She is happy." Here, "she" is the subject, "is" is the linking verb, and "happy" is the adjective that describes "she."
• A conjunction is a word that connects words, phrases, or clauses. There are three types of conjunctions: coordinating, subordinating, and correlative. "But" is a coordinating conjunction because it joins two independent clauses of equal importance.
• "The former" and "the latter" are used to avoid repetition and refer to the first and second of two people, places, or things mentioned earlier in the sentence.
• A comparison phrase is used to compare two or more people, places, or things. There are three types of comparison phrases: comparative, superlative, and equal. "Greater than" is a comparative phrase that shows that Kabir is superior to Rahim.

In conclusion, the error is in part 4, and the correct sentence should be "Kabir and Rahim are great poets but the former is greater than the latter."