Which type of sentence structures needs only a subject and predicate in agreement order to be correct?

The type of sentence structure that needs only a subject and predicate in agreement order to be correct is a simple sentence.

Here's why:

* Simple sentences are the most basic sentence structure. They consist of one independent clause, meaning they express a complete thought on their own.

* Subject-predicate agreement is essential for all sentences, but it's the core element in a simple sentence. The subject performs the action, and the predicate tells what the subject does or is.

Examples:

* The cat sleeps. (Subject: "cat", Predicate: "sleeps")

* She runs quickly. (Subject: "she", Predicate: "runs quickly")

* The sun shines brightly. (Subject: "sun", Predicate: "shines brightly")

Note: While simple sentences are the most basic, they can be expanded with modifiers (adjectives, adverbs, phrases) to add detail. However, the subject-predicate core remains the essential structure.