Which sentence demonstrates correct comma usage?

The sentence that demonstrates correct comma usage is the one that states, "Whenever it's cold outside, I grab a blanket and a warm cup of tea." This sentence effectively uses a comma to separate the introductory clause "Whenever it's cold outside" from the main clause "I grab a blanket and a warm cup of tea." In standard English, it is common to place a comma after introductory phrases or clauses to clarify the sentence structure and enhance readability.

In this case, the introductory clause sets the condition for the action in the main clause, and the comma helps to signal a natural pause, making it easier for the reader to understand the flow of the sentence. Proper comma usage in this context not only adheres to grammatical conventions but also improves the overall clarity and effectiveness of the sentence.

In contrast, the other sentences either lack necessary punctuation or misuse commas in a way that could confuse readers. For example, the first two sentences could benefit from commas to clarify the relationship between clauses, while the last sentence lacks proper structure to effectively convey the list of actions being discussed.