Which of the following sentences contains a comma splice?

The sentence in option D is considered to contain a comma splice because it incorrectly connects two independent clauses with only a comma, which leads to a grammatical error. An independent clause is a group of words that can stand alone as a sentence because it expresses a complete thought. In this case, "It is important to till the soil" and "this simple part of the process yields big results" are both independent clauses. When combining these two clauses, a coordinating conjunction (like "and," "but," or "so") or a semicolon should be used instead of just a comma. This way, the relationship between the two ideas is clearly established, and the sentence becomes grammatically correct.

Recognizing a comma splice is important in writing because it helps maintain clarity and coherence within your sentences, allowing readers to understand your ideas more effectively.